Nano-engineered coatings and thin films: from design to applications

Resume : For state-of-the-art devices there is a strong interest in improving nanoscale fabrication techniques such as atomic layer deposition (ALD). Particularly plasma-assisted ALD processes are considered an enabler for a wide range of applications because of their enhanced reactivity. For instance to allow deposition at low temperatures, allow films with higher material quality, or to engineer films and surfaces to have specific properties. This contribution discusses several effects present in plasma ALD which have been investigated in recent years and found to have a strong influence on the ALD process and resulting material quality. Besides reviewing the basics of plasma ALD, two aspects will be discussed. First the effect of gas residence time on plasma ALD will be discussed and how it relates to a redeposition effect which has been found to be especially important for silicon nitride. Secondly, the effect of ion energy and its control will be discussed. Ion energy can be reduced to negligible values to avoid any influence but can also be enhanced through substrate biasing to improve and tune material properties. An overall physical picture of the plasma ALD process will be described and an outlook on possible trends will be presented.

Resume : Within the materials deposition techniques, Spatial Atomic Layer Deposition (SALD) is gaining momentum since it is a high throughput and low-cost alternative to conventional atomic layer deposition (ALD). SALD relies on a physical separation (rather than temporal separation, as is the case in conventional ALD) of gas-diluted reactants over the surface of the substrate by a region containing an inert gas. Thus, fluid dynamics play a role in SALD since precursor intermixing must be avoided in order to have surface-limited reactions leading to ALD growth, as opposed to chemical vapor deposition growth (CVD). Fluid dynamics in SALD mainly depends on the geometry of the reactor and its components. To quantify and understand the parameters that may influence the deposition of films in SALD, the present contribution describes a Computational Fluid Dynamics simulation that was coupled, using Comsol Multiphysics®, with concentration diffusion and temperature-based surface chemical reactions to evaluate how different parameters influence precursor spatial separation. In particular, we have used the simulation of a close-proximity SALD reactor based on an injector manifold head. We show the effect of certain parameters in our system on the efficiency of the gas separation. Our results show that the injector head-substrate distance (also called deposition gap) needs to be carefully adjusted to prevent precursor intermixing and thus CVD growth. We also demonstrate that hindered flow due to a non-efficient evacuation of the flows through the head leads to precursor intermixing. Finally, we show that precursor intermixing can be used to perform area-selective deposition.

Resume : The development of nanostructured thin layers is of great interest for a wide range of application fields (optics, plasmonics, catalysis, sensors, …). In the domain of photo-catalysis, titanium dioxide is widely used for its excellent properties. This work was focused on the fabrication and the characterization of inverse opal structures that could be used as a catalyst thanks to their large specific surfaces. TiO2 thin films were obtained by Atomic Layer Deposition (ALD) on polystyrene nanobeads orderly deposited on silicon substrates. ALD process allows the growth of dense and conformal layers with a perfect control of the thickness. The deposited layers can even cover holes and cavities unlike classical CVD. An inverse opal structure of titanium dioxide is obtained by burning the polystyrene beads in a post-annealing process. As a photocatalyst, the absence of absorption bands in the visible range is the main defect of TiO2. Many studies have been led to solve this problem by introducing noble metals nanoparticles in a TiO2 matrix. This aim of this work is to synthesize Au/TiO2 composites with an inverse opal structure by ALD and to study the effect of the coupling between gold nanoparticles and TiO2 matrix on the photocatalytic properties of TiO2. The composite properties (morphology, structure, catalytic properties, …) were studied with different characterization tools (SEM, TEM, XPS, Raman spectroscopy, optical absorption spectroscopy, …). First results showed a good distribution of Au nanoparticles in the TiO2 matrix of the inverse opal structure. Optical absorption spectra revealed an important shift of the absorption peak of gold nanoparticles when they are surrounded by TiO2, attesting the effect of the coupling between the two materials.

Resume : Nickel is a ferromagnetic transition metal with a fcc structure, it has a low electrical resistivity and a good resistance to oxidation. Nickel has recently shown benefits in a wide range of domains, from catalysis to energy storage devices. In particular, nickel magnetization makes it useful in several topical fields such as magnetic resonance imaging or spin-controlled electronic devices. In this context, developing novel and specific nickel thin films are of important interest, especially for nanotechnology. In this work, thin films of nickel achieved on (100)- and (110)-oriented SrTiO3 substrates using a pulsed laser deposition method are presented. The surface morphology and structural properties were investigated by XRD and AFM. Epitaxial growth was highlighted by pole figures. Phi scans and reciprocal space mapping, however, reveal that the films growth on (110)-SrTiO3 have two in-plane and out-of-plane orientations. The unit cell of nickel is rotated in the plane of the film by ±5° and out of the plane by ±3.7°. Surface energy modeling by first principles calculations makes it possible to explain the observed growth by low surface energy anisotropy. In addition, oxidation resistance of the films has been studied by in situ high-temperature XRD. Results show the formation of a NiO oxide layer which retains the initial orientation of the Ni film. Depending on the substrate, the Ni corrosion temperature varies from 375°C to 500°C. Such difference is linked to their density and surface morphology, and results are in agreement with AFM analysis. Furthermore, thin films exhibit a homogeneous and nanostructured surface.

Resume : A modified version of HiPIMS, called Deep Oscillation Magnetron Sputtering, with a pulsed reactive gas flow control and to-substrate reactive gas injection into a high-density plasma in front of the sputtered molybdenum target was used for low-temperature deposition of Mo-O(-N) films. The depositions were performed using a strongly unbalanced magnetron with a planar molybdenum target of 100 mm diameter in argon-oxygen(-nitrogen) gas mixtures at the total pressure close to 1 Pa. Voltage macropulses, composed of 5 voltage micropulses (pulse-on time of 23 µs and pulse-off time of 27 µs), with a total length of 250 µs and repetition frequency of 400 Hz were used for all depositions with a maximum target power density up to 1150 Wcm-2 during pulses at a deposition-averaged target power density of 10 Wcm-2. The substrate temperatures were less than 120 °C (no external heater) during the depositions of films on floating glass and Si substrates at the distance of 100 mm from the target. A pulsed reactive gas flow control made it possible to produce high-quality MoOx and MoOxNy films with a tunable composition, and optical and electrical properties. The luminous absorption of 4% for 1 µm thick non-conductive MoO3 films (the luminous transmittance of 80%) was smoothly changed into 88% for conductive (electrical resistivity decreased by up to 10 orders of magnitude) MoOx or MoOxNy films, keeping hardness of 3-5 GPa and very low macrostress (less than 200 MPa).

Resume : Semiconductor photocatalysts are of interest for many applications including energy conversion, pollution reduction and antimicrobial applications. Titania nanoparticles have been widely studied in this field, but require containment, fixation and recovery. Visible light activity in titania has been demonstrated through doping, e.g. with N, or formation of mixtures of materials, e.g., anatase nanoparticles with graphene oxide. Facet-engineered nanoparticles have been shown to yield excellent behaviour, but are not confined to a surface.The toxicity to humans and the environment from nanoparticles is another concern. In this work, we study the performance of nano-structured titania films that are grown from a single precursor solution by pulsed pressure MOCVD, a facile, scalable growth technique. The durable and adherent films comprise a mixture of anatase, rutile and carbon. The anatase possesses an unusual [220] texture with a very high surface area, nano-structured, dendritic morphology. The rutile has a polycrystalline branched structure. Amorphous carbon is distributed throughout the films. The development of photocatalytic activity was studied incrementally with film thickness by adjusting the number of growth pulses. The antimicrobial activity was determined in the dark and under UV and visible light. The relations between structure and activity will be discussed in this paper.

Resume : We present a simple method based on the microwave absorption by metallic wires that can be used for thin film deposition. The films were grown on quartz and Si substrates at room temperature from pure 0.5 mm diameter W, Pt, and Pt-Rh wires under Ar, CO2 or N2 atmosphere. For the vaporization and ionization process of the metallic wires we used a microwave generator with a 2.45 GHz frequency at 800 W. Briefly, the microwave generator arrangement is composed of a power supply, a microwave source and a cylindrical cavity having the 〖TM〗_011 propagation mode. In this experimental set-up we vaporized and ionized the wires by direct interaction with the microwave field from the cylindrical cavity. The electron temperature reached by the generated plasma was estimated using the ratio of atomic emission lines acquired by a high definition optical multichannel spectrometer. The structure and morphology of the deposited films were investigated using X-ray reflectivity, grazing incidence X-ray diffraction, and scanning electron microscopy while the chemical composition was investigated using X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The results showed that the chemical interaction with the gaseous atmosphere could change the chemical composition of the deposited films. The properties of the deposited films, which could be used for sensors or protective coatings were correlated with their structure, surface morphology and chemical composition.

Resume : Most of the current applications based on films use compact polycrystalline films. The stress field determines the properties of the films and affects the lifespan of devices. The evolution of the intrinsic stress during the preparation of polycrystalline films has been investigated over decades. Nowadays, it is well known that the compact films grow under compression, whose strength is closely linked with the density of grain boundaries (GB). However, the origin of the compression has not been clarified yet despite many models have been proposed. Recently, we measured the local distribution of residual intrinsic stress in polycrystalline films using a method of nanoscale stress mapping based on AFM. Our results demonstrated that, at odds with expectations, compression is not generated inside GBs, but at the edges of gaps where the boundaries intercept the surface. We report now a “definitive” model, wherein the compression is caused by Mullins-type surface diffusion towards the GBs, which generates a kinetic surface profile different from the equilibrium profile predicted by Laplace-Young. Where the curvatures of both profiles differ the intrinsic compression rises in the form of Laplace pressure. Our model addresses successfully all the major evidences reported so far regarding the behavior of stress with experimental conditions. [1] Polop, Vasco, Perrino, Garcia, Nanoscale 9, 13938 (2017) [2] Vasco, Polop, PRL 119, 256102 (2017) [3] Vasco, Michel, Polop, PRB 98, 195428 (2018)

Resume : Controlling the morphology and the residual stress in thin films after the growth of materials is crucial to tailor their properties. Although the presence of residual stress in a thin film is in general considered as a drawback, however in some particular cases, it can be of real benefit for the desired application. In this contribution, we show how the residual stress in a deposited gold copper alloy by magnetron co sputtering can be used to tune the morphology of nanoporous gold after dealloying. Deposition of a gold copper thin film was performed over a substrate at different temperature leading to different morphologies of the thin film according to Thornton diagram. Dealloying those thin films in nitric acid lead to an island like nanoporous morphology for high deposition temperature. The origin of such innovative morphology is attributed to the remaining stress in the sample after deposition. More precisely, it has been demonstrated that the residual stress is mostly due to the thermal stress induced during deposition. In this study, the remaining stress in as-grown films was studied by an X-ray diffraction study and the nanoporous structure was probed by Small Angle X-ray Scattering and Scanning Electronic Microscopy. Such nanostructured gold thin film with a double level of porosity can be considered as potential candidates for the development of advanced sensors and actuators.

Resume : Smart nano-multifunctional complex oxide heterostructures such as metal insulating transition (MIT) thermoelectric thin films and free-standing nanowires have recently received a renewed attention due to their promising novel nanotechnological applications and breakthrough in femtosecond switching, sensing, energy-efficient smart windows and information storage technology. There are several factors, which make this review particularly timely and important. Firstly, there is a market pressure, primarily from the nanoelectronic industry and energy sectors to develop highly efficient novel multifunctional optoelectronic devices through process optimisation and band gap engineering. Secondly, there is an opportunity for novel exploration and breakthrough at material interfaces due to the recent R&D in thin film growth and nanofabrication technology. Thirdly, there is a need to investigate intrinsic size effects on the MIT oxides at nanoscale in the absence of extrinsic factors in order to fully understand their performance. This feature review attempts to discuss and compare thin film deposition and nanofabrication techniques used to fabricate vanadium dioxide (VO2) MIT thin films and free-standing nanowires. In particular, the evolution of pulsed laser deposition (PLD), Physical vapour deposition (PVD), plasma enhanced chemical vapour deposition (PECVD), thermal evaporation, sputtering and focused ion beam (FIB) systems are technically and critically reviewed. Keywords Thin Film Nanotechnology, Multifunctional Oxide Heterostructures, Nanowires, Self-assembly, Thermoelectric Materials, Metal Insulating Transition, Band Gap Engineering, Process Optimisation, Size Effects.

Resume : Formation and properties of atomically thin metal films on two-dimensional substrates is a cutting-edge research due to the extraordinary potential for next-generation applications in biomedicine, nanoelectronics, and environmental sensorics. The integration of silver (Ag) films with graphene is a suitable strategy to design new materials with tuneable optical, electronic and catalytic properties. For instance, graphene/Ag-nanoparticle hybrid systems can be used in optical sensing and Raman imaging, in which the analysis of molecules and biomaterials is facilitated by the surface enhanced Raman scattering (SERS) provided by the plasmonic silver nanoparticles. Here, we present a detailed investigation of the formation of ultra-thin Ag films deposited on epitaxial graphene/SiC by magnetron sputtering and their effect on the vibrational properties of graphene. Silver films were deposited at room temperature with nominal thicknesses ranging from 2 nm to 30 nm. Morphological and structure properties were studied by SEM, XRD, C-AFM and HRTEM, while the vibrational properties were probed by Raman spectroscopy. The characteristic Raman modes of epitaxial graphene with silver deposits suggest a strong surface plasmon-phonon interaction. Average SERS enhancement factor for G mode increased with the increase of the Ag film thickness, reaching the maximum value for the 15 nm film (a factor of 73). Models explaining the effect of Ag on the Raman spectra of epitaxial graphene are proposed and discussed.

Resume : Thin films technology is developing to improve the surface properties and material characteristics. Thin films can be used individually or in combination depending on the specific requirements and application field. Thereby, the elastic behavior is important to be known in order to assess the mechanical behavior of thin films and to design reliable components. The purpose of this study is to develop the Impulse Excitation Technique (IET) and to determine its limits for measuring the macroscopic elasticity constants (ECs) of in-plane anisotropic multilayer thin films. The IET is based on the analysis of vibrational frequencies created by an impact on a specimen. It is used to characterize the elasticity of films at the macroscopic scale [1-2]. Finite element analysis was carried out to validate the assumptions made in the analytical models which are used to compute the ECs from the vibration frequencies. New developed models were validated for multi-coated substrate and in-plane anisotropic coatings and were applied to Nb/Ti bilayer thin films, deposited by magnetron sputtering. Metallic films (e.g. tungsten (W), Titanium (Ti)) were deposited with Glancing Angle Deposition to achieve an in-plane anisotropy. Generally, thin films are textured, multiphased and porous. Thereby, the determination of their macroscopic ECs is not sufficient to predict their mechanical behavior. Therefore, we determine also the single-crystal ECs of different phases included in the film. A multiscale methodology (self-consistent) allowing the determination of these ECs of a phase included in a multiphased coating was developed taking into account its texture, multiphased character and the porosity. This was applied to determine the single-crystal ECs of the Wβ metastable phase embedded in a biphased W film (Wα Wβ). Keywords: Coatings, Elastic constants, Anisotropy, Multilayers, Impulse Excitation Technique, magnetron sputtering, PVD, texture, multiphase, X-ray diffraction. References: [1] M.F. Slim, A. Alhussein, F. Sanchette, B. Guelorget, M. François, A new enhanced formulation to determine Young's and shear moduli of thin films by means of Impulse Excitation Technique, Thin solid films 631 (2017) pp. 172-179. [2] M.F. Slim, A. Alhussein, A. Billard, F. Sanchette, M. François, On the determination of Young’s modulus of thin films with Impulse Excitation Technique, Journal of Materials Research 32 (3) (2016) pp. 497-511.

Resume : Recently group IB metal (Au, Ag, Cu) plasmonic nanoparticles were considered as self saturable absorber mirrors for fiber lasers. In this case copper have some advantages over Au or Ag such as compatibility with semiconductor device technology and its abundance. Properties of the plasmonic nanoparticles can be additionally controlled by growing nanocomposites. Diamond like amorphous carbon (DLC) is very good candidate as a nanocomposite matrix material. DLC films received significant attention to their high hardness, wear and corrosion resistance as well as possibility to change electrical and optical properties of these films in a wide range. In this study hydrogenated and hydrogen free DLC films as well as DLC nanocomposites with embedded Cu nanoparticles (DLC:Cu) were deposited by direct (DC) magnetron sputtering and high power impulse magnetron sputtering (HIPIMS). Chemical composition and structure of the films was varied in a broad range by changing deposition conditions. Composition and structure of the films were studied by Raman scattering spectroscopy, X-ray photoelectron spectroscopy (XPS), He ion microscopy and atomic force microscopy (AFM) were used. Cu atomic concentration in DLC:Cu films varied in 0-60 at.% range. Very different sizes of the Cu nanoclusters was observed in nanocomposite films grown by using different deposition conditions. Structure of the DLC matrix varied in broad range, too. Despite that, the maximum of the surface plasmon resonance peak of the absorbance spectra was in 600-700 nm range for all studied DLC:Cu films. Nonlinear optical properties of the selected samples were investigated. Possibility to use DLC:Cu films as self saturable absorbers for fiber lasers was considered.

Resume : TiO2 thin films grown by ALD are used in various fields of application. The required processing conditions vary according to the targeted application to have amorphous or crystalline films, dense or porous layers, low-temperature process or not, etc. We have explored the variation of TiO2 crystallinity, optical thickness, composition and porosity upon variation of ALD process (precursor and substrate temperature) and subsequent heat treatment (temperature and duration). TiO2 has been synthetized from titanium tetraisopropoxide (TTIP) or tetrakis(dymethylamido)titanium (TDMAT) and water at temperatures ranging from 70 to 250°C. The heat treatment was performed in air after the ALD, for 5 to 240 minutes at temperatures ranging from 100 to 450°C. The refractive index of as-grown films increases with deposition temperature when TTIP is used but is roughly constant for TDMAT. The growth per cycle (GPC) is higher when TDMAT is used as well as the refractive index. A systematic loss of thickness subsequent to the heat treatment has been observed for titania grown at 70 to 150° from TTIP. The thickness loss is higher for lower deposition temperatures and comes along with an increase of the refractive index. For samples made from TDMAT at temperatures as low as 90°C and samples made from TTIP at 200°C and above there is no thickness loss. All the samples that were stable during heat treatment were stable in KOH. Likewise, samples that shrunk during heat treatment failed to protect the silicon from KOH attack. The composition and the structure of the films have been investigated by FTIR, XRD and ellipsometry porosimetry to understand the relation between the chemical instability and the dependence of refractive index and thickness loss on process conditions.

Resume : Biocompatible and biodegradable materials are of high interest for tissue engineering, drug delivery and wound healing and their development is required for a new generation healthcare materials. It is considered that most of the common polymers used for biomedical applications, such as polylactic acid (PLA) and polycaprolactone (PCL) are not capable to sufficiently support the cell growth. When we are talking about the nanofibers prepared from these biodegradable polymers, their hydrophobicity is increasing even more and, as result, the biocompatibility of these materials will be very low in spite that the structure of nanofibers is similar to the extracellular matrix. Hence, in order to apply the biodegradable nanofibers for wound healing or tissue engineering applications, their surface properties must be tuned accordingly. The deposition of thin plasma coatings containing amine or carboxyl groups opens the possibility to adjust independently the surface chemistry, wettability and charge. Here we are reporting the methodology to coat electrospun PCL nanofibers by COOH coatings in order to graft the bioactive molecules and antibiotics via the reactive surface groups. The density of COOH groups can be controlled by ratio of CO2 and C2H4 gases in the plasma gas mixture. The XPS results confirmed the grafting of bioactive molecules and their release rate depends on the stability properties of plasma layers. Our in vitro and in vivo results demonstrated that the modified nanofibers has high potential for tissue engineering. Authors gratefully acknowledge the financial support of the Russian Science Foundation (grant No. 18-75-10057)

Resume : Direct methane-fueled solid oxide fuel cells (DM-SOFCs) are promising next-generation energy conversion devices that show advantages such as easy storage, low manufacturing cost and infrastructure for fuel. The DM-SOFC system can also be configured without any further reforming procedures. However, slow anode kinetics and carbon coking on the anode surface at low temperatures may reduce the performance and stability of the SOFC. Ruthenium (Ru) is a well-known methane oxidation catalyst with carbon coking resistance by converting methane by partial oxidation and reforming. However, Ru shows poor thermal stability when it is fabricated in the nanoporous structure for high performance due to high surface free energy. In this paper, we deposited conformal ALD YSZ overlayer on porous Ru anode with thicknesses of 10, 20 and 40 nm (namely, Ru 10YSZ, Ru 20YSZ, and Ru 40YSZ, respectively). Nano-crystalline ALD YSZ has penetrated into the pores of Ru anode as observed by a Cs-corrected scanning electron microscope (Cs-corrected TEM). Ru 20YSZ exhibits the highest performance (3.5mW/cm2 @ 450°C) among the cells. In addition, Ru 20YSZ and Ru 40YSZ maintain high OCV (~0.9V) for 10 hours with reduction rates of 5.6 and 4.0%/hr only, which is significantly improved compared to the bare Ru anode cell (i.e., OCV drops to 0.1 V in one hour). Coking behavior at anode surface is also characterized by using high-resolution X-ray photoelectron spectroscopy (XPS).

Resume : Mechanoresponsive diacetylenes (DAs) exhibiting a transition of crystalline orientation from light-inert to light-active state upon applied force are introduced. Amide units are introduced to DAs where hydrogen bonding is utilized to control intermolecular interactions. Application of external pressure (2−150 MPa) to DAs resulted in an emergence of new crystal phases which reduced the reaction barrier. Accordingly, the dramatic crystalline transition from “perfectly off” to “on” state to undergo the light-induced topochemical polymerization of bulk DA crystals was obtained. Subsequent UV irradiation at a wavelength of 254 nm enabled the polymerization of the pressed region, changing its color from white to blue which suggests the selective formation of polydiacetylene (PDA) polymorphs. As a result, by utilizing the mechanoresponsive crystallinity with low-enough activation pressure, a new strategy for PDA patterning is demonstrated based on the selective transfer of information by means of force to a DA film. This phenomenon can be applicable to a new nanoimprinting technique where no mechanical deformation of resist materials but phase transition is induced by the mold.

Resume : Mn2RuxGa (MRG) is a half-metallic ferrimagnet, exhibiting strictly zero moment at a precise temperature (T_comp) that depends on Ru doping x and substrate-induced bi-axial strain, while concurrently maintaining its spin-polarisation. The combination of no net moment and anisotropy make MRG suitable for high-frequency (0.2-2 THz) applications. MRG-based magnetic tunnel junctions (MTJs) using an MgO spacer have, so far, shown the best MR values, limited by the instability of the MRG/MgO interface resulting in Mn oxidation and interdiffusion. This leads to inferior MgO quality, decreasing the TMR ratio, as well as reduced MRG magnetic anisotropy. Here we explore novel spacer layers (TiN, Hf, HfOx, V and Mo), and demonstrate their effectiveness when the magnetoresitive stacks are subjected to a thermal anneal at 350oC. Mo and Hf are shown to prevent diffusion, maintaining the structural and magnetotransport properties of the device, and show potential for expitaxial growth on MRG. The full stack is MgO//Mn2Ru0.7Ga(30)/x(t)/[Co(0.4)/Pt(0.8]8/Co(0.4)/Pt(3), (thickness in nm), x is the spacer, and t its thickness (2 nm and 1.4 nm).

Resume : Evaporative drying of saline water droplets on solid substrates is a complex yet interesting field of research in last few decades. A simple but novel approach is used to fabricate oriented nano as well as micro-crystalline domains of NaCl over large area using line nano-patterned and bio-mimicked (from rose petals) Polydimethylsiloxane (PDMS) templates simply by evaporation-mediated drying of dilute NaCl-Methanol solutions. Reasonably dilute methanol-based salt solutions causes significant droplet spreading and initially anisotropic droplet shape induced by nano-patterning is transformed into almost spherical one due to faster retraction of wetting front along the lines in the solvophilic direction. Within the final uniform thin film deposits salt nano-patterns are preferentially oriented within the grooves of the nano-lines as observed through high resolution field enhanced scanning electron microscopy (FESEM) studies. The same dispersion droplet gets pinned after spreading when dispensed on negative rose petal replica (NRPR) giving rise to bigger deposits. FESEM measurements reveal small micron-sized (ca. 5µm) single cubic crystalline structures uniformly deposited within each trough of NRPR over the whole deposit area. Varying salt concentration seems to influence the crystal size within the troughs of NRPR. Increased salt concentration reduces the initial spreading of the droplet leading to small-sized final deposit and bigger-sized single crystals within troughs.

Resume : Polymer electrolyte membrane fuel cells (PEMFCs) have received attentions as a next-generation eco-friendly energy conversion system, especially for future vehicles. However, the high price and low stability of platinum (Pt) catalysts are considered to be the biggest obstacles in the full commercialization of fuel cell electric vehicles (FCEV). Recently, atomic layer deposition (ALD) has been successfully utilized for synthesizing nanoparticle catalysts in various fields with unique properties including accurate thickness and composition control and conformal deposition even along complex-shaped substrates. In this study, Pt nanoparticles for PEMFCs were successfully deposited on carbon nanotube (CNT) surfaces by ALD. Optimized oxygen plasma pretreatment was key to promoting conformal growth of ALD Pt on CNTs and reduced the ALD incubation time, which is critical for quality and yield. The ALD Pt-CNT nanostructure was evaluated as the cathode catalyst layer of the PEMFC MEA (membrane electrode assembly). As a result, very high stability of the ALD Pt-CNT catalyst was observed during the accelerated stress test (AST) preserving a high power output in cell tests. This result will be discussed in more details at the presentation.

Resume : Composite hetero-tribological coatings (HTC) that based on MoS2, WS2, etc. of thin films are discussed. One of the ways to improve wear resistance and strength of solid lubricant coatings (SLC) is their together joint use with a hard and wear-resistant materials in composite structures of the films. And with the other hand, the properties of the hard coatings may be improved with the SLC adding. The paper considers the various composite structures of the hetero-tribological coatings, including variants based on discrete planar elements. Hetero-tribological coatings based at the magnetron sputtering deposition technology are presented. The influences of the HTC composite structure components synergetic effects on the coating properties are studied.

Resume : So far, I have reported the results of experiments and molecular dynamics (MD) simulations of organic graphoepitaxy, that is, oriented thin film growth of organic semiconductors such as sexithiophene (C24H14S6) and pentacene (C22H14) on micro-grooved substrate surfaces fabricated by electron beam lithography [1-4]. Through these studies, I found that MD simulations were useful in reproducing experimental results of organic graphoepitaxy, and these results naturally led me to the MD simulations of organic semiconductor thin film growth on simple flat surfaces. However, owing to the limitation of time and the number of molecules which can be treated within the limited capability of computation, it seems hard to reproduce the process in which rod-shaped molecules such as pentacene stand up spontaneously on flat surfaces by MD simulations though standing structure is universal in the actual thin films. Therefore, I changed the strategy of simulations and I started to evaluate the stability of clusters comprising standing pentacene molecules on flat substrate surfaces. It was found that clusters consisting of more than thirty standing molecules could exist stably on hydrophobic flat surfaces (more than 100 molecules were necessary for stabilization on hydrophilic flat surfaces) and could grow by incorporating surrounding molecules. [1] APL (2006) DOI: 10.1063/1.2216375 [2] JAP (2008) DOI: 10.1063/1.2913180 [3] JJAP (2018) DOI: 10.7567/JJAP.57.03EG04 [4] E-MRS 2018 Spring Meeting (Strasbourg) V3.3.

Resume : Transparent electrodes, which are optically transparent to visible light and electrically conductive, have been an essential component for liquid crystal displays (LCDs), organic light emitting diodes (OLEDs), organic photovoltaic (OPV) cells and touch panels. Currently, indium tin oxide (ITO) is the most widely utilised transparent electrode due to its excellent optoelectrical properties, comprising of a sheet resistance (Rs) of 10?15 ?/sq and >85% transparency at 550 nm. To meet the requirement of current optoelectronic devices, scalable production of high quality electrodes with advanced properties such as high optical transparency and electrical conductivity is vastly demanded via low-cost approaches. In addition to the conductivity and transparency, flexibility is becoming more and more attractive since flexible electrodes have the potential to open new applications and markets. The new applications require transparent electrodes to be flexible, cheap, and compatible with large scale manufacturing methods. In consideration of these conditions, ITO is a less favourable candidate for future transparent applications due to its high materials cost of indium as well as the high manufacturing cost . Instead, there has been a wide range of materials as alternatives to ITO such as metal nanowires, graphenes and conjugated polymers. As one of the promising alternatives to ITO, AgNW films have been demonstrated to provide high flexibility, high transmittance and low sheet-resistance comparable to that of ITO. It is easy to deposit AgNW on different substrates via low-cost and scalable manufacturing techniques. Importantly, inkjet printing is a promising technique for large-scale printed flexible and stretchable electronics. However, inkjet printing of silver nanowires (AgNWs) still presents many challenges. In this study, inkjet printing of high-concentration AgNW ink on flexible substrates is demonstrated. We analyzed the relationship between the surface microstructure and electrical property of the printed AgNW layers. The high transparent and conductive performance in coupling with the simple and scalable manufacturing process could secure practical products as an alternative to ITO for advanced optoelectronic applications. In our case, all inkjet printed organic modules with efficiency exceeding 4 % deposited from environmentally friendly solvents in an air atmosphere are demonstrated. [1]Lee J, Petruska MA, Sun S. Surface modification and assembly of transparent indium tin oxide nanocrystals for enhanced conductivity. J Phys Chem C 2014;118:12017e21.]. [2] Kim A, Won Y, Woo K, Jeong S, Moon J. All-solution-processed indium-free transparent composite electrodes based on Ag nanowire and metal oxide for thin-film solar cells. Adv Funct Mater 2014;24:2462e71. [3] Stapleton Andrew J, Ellis Amanda V, Shapter Joe G, Andersson Gunther G, Quinton Jamie S, Lewis David A. Highly conductive interwoven carbon nanotube and silver nanowire transparent electrodes. Sci Technol Adv Mater 2013;14:035004.]

Resume : Human fingerprints are randomly created by folding of skin starting around 10 weeks old and the pattern of the folds on skin changes with every touch by fetal activity inside the womb. Thus difference in the activity of fetus results in unique fingerprint pattern. This feature is not physically reproducible and has been utilized as a cryptographic primitive. Filamentous M13 bacteriophage can accommodate a template for single walled carbon nanotubes (SWNT) to be entangled with each another and consequently to create random SWNT networks. Stochastically knitted SWNT networks exhibit inherently random and unique electrical characteristics to be exploited as a physical unclonable function (PUF) for authentication. Challenge-response pairs (CRPs) should be formulated for authentication with PUF. In this research, M13-mediated SWNT networks are investigated to map out the resistance profile between two adjacent electrodes, which is determined by random process variation of the SWNT network on the M13 platform. Moreover, the random process variation leads to the unique resistance profile of each M13-SWNT device as exactly the same as human fingerprints. With the known resistance profile, the combinations of the electrodes become the challenges and those are surely answered by the predetermined resistances between the selected electrodes as the responses. In order to translate the resistance distribution of the M13-SWNT device into the response bits, the resistance range is divided into 8 levels and each level is assigned to one of 8 different 3-bit long strings, 2^3, eventually comprising the response bits. Through this scheme, the CRPs are generated and evaluated in terms of randomness, uniqueness and bit-error-rate.

Resume : Light management is one of the main challenges in ultrathin Cu(In,Ga)Se2 solar cells, due to the absorber layer being too thin (500 nm) to absorb long wavelength photons when comparing with the standard CIGS thickness ( 2 µm). To address such optical loss, eight metal layers and metal alloys (interlayers) are employed between the rear contact Molybdenum (Mo) and the material used for the rear passivation, aluminium oxide (Al2O3). The interlayers are employed to enhance the optical reflection at the rear thus giving photons another opportunity for being absorbed in the CIGS layer. Thus the following ultrathin CIGS solar cell stack is fabricated: Mo/interlayer/patterned-Al2O3/CIGS/CdS/i:ZnO/ZnO:Al. Optical simulations were conducted for the full solar cell stack to understand the optical influence of the interlayers, followed by the fabrication and electrical characterization of the devices. A detailed comparison between the interlayers is performed to determine which material shows the greatest potential to be employed at the rear in ultrathin CIGS solar cells. A Ti-W alloy shows the most promising results as solar cells with this material achieved a light to power conversion efficiency values of 11 %, which is 1.6 % (abs) higher than the passivated ultrathin sample and 3.6 % (abs) higher than the ultrathin reference sample.

Resume : 3D printing (or additive manufacturing) using powders is a fast-developing technology as it excels in the fabrication of complex 3D objects. However, the range of materials which can be used is limited while desired functionalities of the 3D products (e.g. mechanical stability under stress) become more demanding. The solution to this challenge lies in the integration of material processing within the 3D printing workflow to increase material cohesion and/or to allow the combination of several materials in one object. A previous study introduced the surface modification of PA12 (polyamide 12) powder by plasma treatment [1]. Here, we present an atmospheric pressure plasma functionalization of PA12 microparticles and four alternative powders for application in 3D printing covering a range of polymers and composites. To ensure uniform functionalization of the powders a capacitively coupled radiofrequency plasma jet with a novel design of electrodes is presented, which allows to generate spatially homogeneous and stable plasma across the 9 mm plasma column diameter [2]. The geometry also integrates a powder supply pipe to introduce particles into the plasma column for efficient workflow and consistent treatment. The functionalization of particles was analyzed by XPS, FTIR and SEM. [1] A. Almansoori et al., Plasma Process Polym. (2018) e1800032. [2] J. Schäfer et al., Plasma Phys. Control. Fusion 60 (2018) 014038.

Resume : As the esthetic functions of metals have attracted increasing attention, their colorization is of scientific and technological significance. Here we show that vivid structural colors can be produced on stainless steel (STS) and Al, which are two of the most commonly used metals. It is well known that a transparent dielectric layer coated onto a substrate exhibits a rippled reflectance spectrum consisting of alternating reflectance minima and maxima due to multi-beam interference, making it appear colored. However, such a layer does not produce strong colors on a highly reflective metal like Al because the resulting interference ripple has small amplitudes. We were able to generate very vivid colors by coating a thin metal layer over the dielectic layer, where the metal layer plays a role to adjust the amount of light incident into the dielectric, ultimately strengthening the interference effect. The hue and saturation of the produced colors were controllable with the thicknesses of the dieletric and metallic layers, respectively. Simulation based on the finite-difference time-domain method supported the experimental results. Colors images could also be printed by locally controlling the thicknesses of the overlayers. This method has the potential for a variety of applications ranging from surface decoration and visual arts to optical filters and perfect absorbers.

Resume : Vertical crosslinked gradients in surfaces are potential solutions to meet an increasing demand on innovative design of functional films. Plasma polymerization offers a versatile tool to design physically and chemically stable subsurface gradient architectures comprising a hydrophilic to hydrophobic gradient to study biologically relevant phenomena as e.g. protein adsorption. As distinct from the well-studied parameter, surface chemistry, when considering protein-material interaction, we have explored an additional control over adsorption processes: “the subsurface hydration effect”, generating long-range interaction forces. The vertical gradient structure, nominally 50 nm thick, is realized by hydrophilic SiOx base layers with varying porosity, which can be deposited from hexamethyldisiloxane (HMD-SO)/O2 plasmas, terminated by a nm-thick relatively thin hydrophobic plasma polymerized HMDSO layer. The transition from hydrophobic to hydrophilic layer corresponds to a thick-ness of 2-3 nm underneath the surface detected via angle resolved XPS and TofSIMS. Hydration by water intrusion of such subsurface gradient films was demonstrated by neutron reflectometry measurements. It was recognized that there is a significant reduction in adsorbed protein mass on hydrated gradient films as compared to dry/hydrated reference samples. The entire detailed analysis supports that it is the ferroelectric state of water molecules confined in the amphiphilic subsurface gradient which generates dipolar fields that remarkably affect adsorption of proteins. Thereby, the development of a successful approach to modulate initial protein adsorption is accomplished which is relevant for tissue engineering, smart materials etc.

Resume : Bulk optics have been used for various optical instruments such as microscope or camera, but it has limitations in size and thickness because of accumulation of various lenses. Metalenses are an emerging field as one of the next-generation optical technology for miniaturization of optical system. Subwavelength thick nanostructures on metalens control the amplitude, phase, absorption, emission, and transmittance of incident light. Focal length can be control by adjusting phase shift from 0 to 2π according to the change of shape, size, and period of nanostructures. The development of high efficiency metalens in visible spectrum is one of the significant issue to overcome the limitations of bulk optics. Many kinds of metalens such as GaN nanopillar, Si nanodisk, or TiO2 nanofin have been studied recently, but there is no design rule to control lens characteristics such as focal length and numerical aperture. Therefore it is difficult to adjust the focal length and focal efficiency as desired. In this work, we suggested a general design rule to design specific numerical aperture and focal length in visible spectrum. We used finite-difference time-domain (FDTD) simulation to investigate the effect of geometry of nanostructures on the optical properties. Nanostructures can be designed by controlling size, height, refractive index, and period to maximize the phase shift. Refractive index and period must be maximized within the range of the diffraction limit. In the next step, Metalens can be demonstrated by designing phase distribution so that the phase increases from the center of the lens. Focal length and numerical aperture can be adjusted through phase gradient. As the phase gradient increases, focal length decreases and numerical aperture increases. By using this design rule, focal length and numerical aperture are demonstrated from 50 µm to 500 µm, and 0.5 to 1, respectively. This design rule can attend significant role to demonstrate desired numerical aperture or focal length.

Resume : Flexible plastic substrates have received attention as components in next-generation optoelectronic devices such as organic light-emitting diodes (OLEDs) and organic solar cells because of lightweight, inexpensive, and enable to roll-to-roll mass production. To improve the performance of the devices based on flexible substrates, nano-structuring technology has become indispensable. The planar substrate causes unwanted surface reflection and internal reflection, whereas the nanostructures induce scattering of the light and remove the reflections. Recently, surface modulation of the plastic film has been widely used to enhance the optical scattering of the film such as micro-meshed surface, micro-lens array attached surface, nano-structured surface, and nano-imprinted surface. However, these methods are difficult to maintain stable surfaces because the surfaces are easily damaged by external scratches. Such a problem can be solved with embedding scattering center inside the flexible film. However, it is not easy to control the optical properties of the film due to the difficulty of controlling the scattering center inside the film. In this work, we report the simple and effective method to control the size and the number of the air gaps as the light scattering center by varying the viscosity of protection layer materials and the architecture of the film. Micro-patterns were produced at the surface of polyethylene terephthalate (PET) film by using oxygen plasma treatment. Several colorless curing materials with different viscosity were coated on the micropatterned substrate to analyze the relationship between the air bubbles and the optical haze by controlling the size of embedded air. Also, we design architectures of haze film to capture more air gaps, so more lights were scattered through the film with maintaining total transmittance. The average total transmittance is achieved about 89.1 % and the average haze is achieved about 92.2 % in the visible wavelength region (400 nm < λ < 700 nm) with the double-sided patterned haze film. The haze film effectively diffracts light at the interfaces between the air bubble and the substrate, confirmed by electromagnetic simulation.

Resume : by polar self-assembled monolayers (SAM) is well known and widely used. In this work, we demonstrate this ability using both ionic and molecular induced surface dipoles on Si/SiO2 substrates. The experimental change in the electronic properties such as the work function (WF) and electron affinity (EA), were measured by contact potential difference (CPD) technique and supported theoretically by DFT calculations. A comparison between alkylhalide based monolayers, and amine modified containing halide anions was conducted and regarded as molecular vs. ionic dipole induction. For the first system with alkylhalide monolayers, upon changing the tail group from Cl to I a decreased of the WF of the substrate was observed. However, for the halide anions on modified Si/SiO2 substrates, i.e. self-assembled alkyl ammonium halide (–NH3+ X-, where X- = Cl-, Br-, I-) monolayers, an opposite trend was observed. In this case, upon altering the anions of those halides from Cl- to I-, an increase of the WF was obtained both theoretically and experimentally. Those results were clearly explained by the difference between the ionic and neutral molecular dipoles of the same species. The monolayer' formation was verified by Ellipsometry, X-Ray Photoelectron Spectroscopy and Atomic Force Microscopy measurements. Theoretical and experimental results comparison suggests that ionic surface dipole depends mainly on the position and polarizability of the counter halide anion. Moreover, the organization and packaging of the layer have an important role as well. It is important to notice that using those ionic interactions, an easy way to control and tailor the net surface dipole and electronic properties of Si/SiO2 substrates for various applications is demonstrated.

Resume : Metallic glass has disordered structure that behave mechanically like solids but show catastrophic failure due to short range order structure, and they are generally produced by quenching. Recently, it is observed that the slower cooling rate provides the larger time available for atoms to rearrange structure before freezing in glassy state, leading to glass transition temperature and thermal stability. These glasses with enhanced glass transition temperature synthesized by controlled cooling rate make it useful for various technologies such as wear or oxidation protection material. However, mechanical behavior for metallic glass with extraordinary thermodynamic and kinetic stability has not been studied. In this research, we developed a ultrastable metallic glass thin film by physical vapor deposition process at ambient temperature. Mechanical properties are investigated using in-situ tensile testing and discuss thermal stability and fracture behavior dependent on composition of amorphous metal.

Resume : Mg is a very promising material for lightweight construction and biomedical applications. However, the applicability of Mg and its alloys is hindered by its high corrosion susceptibility. The aim of this study is to develop graphene-polymer nanocomposite thin films for corrosion protection of Mg-alloys. As polymer matrix, poly(4-vinyl pyridine) (P4VP) was selected due to its semiconducting properties and protonic conductivity. In contrast to ICPs with electronic conductivity, the pH-dependant, reversible protonation/de-protonation capability of the P4VP has been utilized to synthesize environment-responsive coatings. Graphene sheets, synthesized via exfoliation of graphite in the presence of perylene tetracarboxylic acid (PTCA) were incorporated as nanofillers to create more tortuous path for the diffusion of corrodants, to minimize percolation effects, as well as to improve the mechanical properties of the nanocomposite coatings. The macroscopic corrosion properties of the nanocomposite coatings were investigated by means of electrochemical methods such as linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in different corrosive media simulating technical and biomedical applications. For both environments significant reduction in anodic corrosion activities have been observed, which indicates a suppression of both Mg-dissolution and anodic hydrogen evolution reactions. Electrochemical studies were complemented by in situ Atomic Force Microscopy (AFM) investigations to analyse localized corrosion processes and coating degradation in the presence of artificial defects as well as under simultaneous corrosive and mechanical load. The presentation will summarize our recent results on the synthesis and characterization of this novel coating system with a special focus on their interfacial stability and corrosion protection properties.

Resume : Many industries are focused on the nano particle metallic inks for the fabrication of electronic devices. silver ink is a typical metallic ink having high conductivity and thermal stability. However, there is a limitation to use it in the fabrication due to its high material cost. Copper is considered as a substitute material for silver, but copper ink has an oxidation issue under atmospheric conditions. Cost effective, highly conductive and oxidation-free copper nano particle ink was synthesized in this study. Copper complexes and copper nano particles were used in the synthesis to prevent its oxidation. Expanding its application to various substrates, the synthesized nano particles were thermally treated at relatively low temperatures in the range of 50~400℃. The prepared copper ink was printed on the silicon substrates and the printed films were then characterized. Each particle of copper complexes and copper nano particles was analyzed by thermogravimetric analyzer (TGA). Sheet-resistance was measured by 4-point probe station. Surface morphology of the prepared electrode was also analyzed using scanning electron microscope (SEM) and transmission electron microscope (TEM). From our results, the synthesized copper ink showed the suitable properties to apply to inkjet printing process for the fabrication of various electronic devices.

Resume : Tailoring of functional coatings and thin films to desired applications requires a precise control of both collective and individual attributes of sub-elements of the coating. Usually this can be achieved by the control of the microstructure and its inner workings (architecture) at the nanoscale. Nano-engineering of the clusters of nanoparticles deposited on a glass substrate gives rise to novel optical elements, which are acting as various mode filters, converters of topological charge or of the chirality of the incident beam etc. A good example of such optical elements are the so-called geometrical phase elements (GPE). Their applications are ranging nowadays from devices like metalenses to special optics and also from wavelengths in the ultraviolet to the THz diapason. The reason behind such flexibility is due to variety of different production approaches – lithography based, glancing angle deposition, patterning processes, deposition of sculptured coatings etc. and due to the varying orientation and individual properties of sub-elements of the GPE. Here, we report on a novel approach in the engineering of such GPE’s using precisely engineered clusters of nanoparticles. We study in detail optical properties of such nanoclusters and investigate how individual properties of nanoparticles are influencing the collective response of a GPE. As a proof of concept we design a functional coating, which acts as a diffractive optical element for laser beam shaping applications.

Resume : Coating materials, especially when applied to flexible electronics, are expected to cover numerous requirements including not only the sufficient barrier performance to prevent device degradation, but also high optical transparency, chemical and scratch resistance, good adhesion, stability, flexibility, and high durability. Known way to achieve desired parameters of polymer materials is by incorporating inorganic nanoparticles (NPs) in the polymer matrix. It has been shown that resulted nanocomposites often display enhanced functional properties when compared to neat polymer. Current contribution targets at designing new coating materials by combining superior properties of siloxane-based hybrid polymers and the reinforcement effect of NP fillers. In this work, Boehmite (BA) nanoparticles were incorporated into Cycloaliphatic Epoxy Oligosiloxane (CEOS) resin. The resulted nanocomposite films were approached by UV light, inducing cationic polymerisation of epoxy groups and, subsequently, the formation of solid polymer network. To evaluate the impact of BA interphase on the film properties, two different types of BA, hydrophilic and organophilic, were applied. CEOS was obtained by non-hydrolytic condensation reaction what was followed by 13C and 29Si NMR. The BA reinforcement effect was evaluated in terms of thermal behaviour using DSC and TGA methods. Observed increase of Tg and thermal stability with BA addition was explained with regard to the chemical changes appeared in the films during photocuring detected by in situ Real-Time Infrared (RT-FTIR) spectroscopy. Additionally, BA agglomeration and distribution was characterised by SEM operated in transmission mode. All the films exhibit optically transparency in visible region.

Resume : The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 14 years, which are motivated for their possible range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses [1]. The synthesis of 1D TiO2 nanotube structure is carried out by a conventional electrochemical anodization of Ti sheet. Atomic layer deposition (ALD) has been shown to be an effective technique to coat TiO2 nanotube layers homogenously with secondary materials [2]. Ultrathin surface coating of TiO2 by secondary materials such as Al2O3 [3], ZnO [4] or MgO [5] annihilates electron traps at the TiO2 surface and thus increases the concentration of the photogenerated charge carriers. This presentation will focus in detail on the coating of the nanotube layers by various secondary materials using ALD. We will show initial photo-electrochemical results for anodic TiO2 nanotubes employed as highly ordered electron-conductive supports for host materials coated using ALD with secondary materials to enhance light absorbing capabilities of such hybrid systems. Experimental details and some very recent photocatalytic [6, 7], sensing [8] and solar cell [9] results will be presented and discussed. References: [1] J. M. Macak et al., Curr. Opin. Solid State Mater. Sci., 2007, 1-2, 3. [2] F. Dvorak et al., Appl. Mater. Today, 2019, 14, 1. [3] R. Zazpe et al., Langmuir, 2016, 41, 32. [4]A. Ghobadi et al., Sci. Rep. 2016, 6, 30587. [5] H. Park, et al., J. Electroceram. 2009, 23, 146. [6] H. Sopha et al., Appl. Mater. Today, 2017, 9, 104. [7] S. Ng et al., Adv. Mater. Interfaces 2018, 5, 1701146. [8] S. Ng et al. Adv. Eng. Mater., 2018, 20, 1700589 [9] R. Zazpe et al., Nanoscale, 2018, 10, 35

Resume : Recently, molybdenum disulfide (MoS2) has been attracted attention as a catalyst for hydrogen evolution reaction to replace the noble metal catalysts such as Pt. In this work, we studied on the in-situ Raman behaviors on MoS2 basal plan during electrochemical treatment for understanding the insight mechanism of the enhancement hydrogen evolution reaction performance. The two main vibrations modes of MoS2 were determined from in-situ Raman spectrometer. The electrochemical treatment of MoS2 was conducted by applying constant current density (1 mA/cm2) using a three electrodes electrochemical experimental set-up with 1M KOH electrolyte. During the in-situ measurements, we found that the vibration frequency and the intensity ratios of above 2 vibration modes were shifted. Further, hydrogen evolution reaction performance was strongly increased. due to the increase of S vacancy defects and the Mo (1010) active site on MoS2 surface during the hydrogen evolution reaction experiment. This research was supported by the Nano•Material Technology Development Programthrough the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (2016M3A7B4904328).

Resume : High-efficiency non-noble metal catalyst has attracted much attention as a potential energy conversion system. To achieve better reactivity, both structural and compositional optimization should be taken into account. Owing to the well-ordered and monodispersed porous structure as well as numerous interconnected channels, inverse opaline films provide larger specific surface area and higher permeability for improved solutes conduction and diffusion. In this work, we employed a simple fabrication process utilizing both electrophoresis and electrodeposition for the production of composite inverse opals. The scaffold could be constructed by either metal or metal oxide, with nanoparticulate copper oxide decorated on its skeleton. Such material combination could be applied as an electrocatalyst for CO2 reduction reaction. The catalytic performance was then evaluated by cyclic voltammetry experiment. The structural characterization for these composite inverse opals was obtained by SEM observation, and EDS, XRD, XPS analysis were performed for their compositional determination.

Resume : Solar blind photodetector is an emerging technology for forest fire, territory intrusion, ozone- hole monitoring, deep space exploration, satellite and security communication. Photodetector working in < 280nm, solar-blind region, could minimise the chances of false radiation detection even under intense sun interference on earth surface by detecting ozone layer filtered deep UV (UV-C) terrestrial signatures. Ideally, an efficient solar-blind photodetector must satisfy 5S requirement i.e., high sensitivity, high signal current-to-dark current ratio, high spectral selectivity, high speed and high thermal stability. On top of all conventional 5 S requirements, ?self-powered? solar blind photodetector has recently grabbed huge attention towards the goal to build intelligent, wireless, exceptionally small and sustainable photodetector. So far, solar-blind photodetectors based on ZnMgO, ZnGa2O4, Zn2GeO4, AlxGa1?xN, In2Ge2O7, LaAlO3 materials is realized by using bandgap tuning through alloying process and optimizing their performance in solar-blind region. However, the process of alloying makes the fabrication complex and introduces high defect density, thereby increases the dark current and limits the performance of solar-blind photodetectors in self-powered mode. Recently, ?-Ga2O3 achieved a vast attention because of its intrinsically solar-blind region bandgap (Eg~4.9 eV), high thermal stability (M.P 1730º C) and chemical stability. In the past few years, a large number of solar-blind photodetectors have been demonstrated on ?-Ga2O3 with different structures including bulk, thin films, and nanostructures. Unfortunately, the high cost and low repeatability of bulk materials and relatively large dark current of individual 1D nanostructure-based devices hinder their practical applications. Therefore, for the point of practical purpose, thin-film type photodetector is favoured owing to their low cost, easy to grow and better repeatable. Thus, for this purpose, numerous research works have been focused on the development of ?-Ga2O3thin film based self-powered photodetector. Despite the impressive developments none of the solar-blind self-powered photodetector structure reported on cost effective and commercialize Si substrate due to its large lattice and thermal expansion coefficient mismatch with ?-Ga2O3. Moreover, the investigated designs reported yet are based on heterojunctions which still suffer from complicated fabrication process and high leakage current which critically affect their performance specially in self-powered mode. Meanwhile, metal-semiconductor-metal deep UV photodetectors (MSM-DUV-PDs) has the merits of simplicity, faster response, low fabrication cost, extremely low dark current, high operation speed and high sensitivity. Therefore, the high performance MSM-DUV-PDs based on ?-Ga2O3 thin films can satisfy the above requirement. However, there is no report for self-powered MSM-DUV-PDs based on ?-Ga2O3 thin film on cost effective substrates for next generation large area production. In this work, we demonstrated an ultra-high-performance and self-powered ?-Ga2O3 thin film solar-blind photodetector fabricated on cost-effective Si substrate using a high-temperature seed layer (HSL). Polycrystalline ?-Ga2O3 thin film deposited with HSL shows high-performance in solar-blind region in comparison to amorphous Ga2O3 thin film deposited without HSL. The zero-bias digitizing sensor prototype with HSL produces a digitized output bit with deep UV (DUV) light. The photodetector shows minimum persistent photoconductivity and fast response in msec. The photodetector yield the responsivity of 96.13 A W-1 with external quantum efficiency (EQE) of 4.76×104 at 5 V for 250 nm monochromatic light. The photodetector shows high response to even rare weak signal of DUV (44 nW/cm2). These values are the highest reported till date for planner ?-Ga2O3 thin film based photodetector despite the use of cost-effective substrate. The asymmetric I-V curve indicates a dissimilar Schottky barrier height (SBHs) at two ends of MSM photodetector and discussed as the main reason for high response even at zero bias. This work provides the guideline to develop ?-Ga2O3 based cost-effective, self-powered, high-performance and fast DUV photodetector which possesses the high potential for next generation practical solar-blind photodetector application. Nevertheless, the sensitivity, responsivity and other critical parameters of any photodetector are mainly affected by the absorption coefficient which is scarcely affected by solely increasing the fundamental properties of the absorbing material. Recently, PNPs have been utilized to improve the performance of the photodetectors due to their ability to increase absorption coefficient beyond the diffraction limit of semiconductors via strong electric field through local surface plasmon resonance (LSPR). Although the PNPs promises high absorption and sensitivity but the free electrons motion near the surface of metals also generates heat by means of ohmic losses. On the other hand, the extreme losses in the form of heat is been utilized by some applications such as steam generation 11, however it offers disadvantage for photodetector devices. As a consequence, ambiguities between various structure parameters have caused conflicts regarding the usefulness of plasmonics in the literature that have inhibited the progressing of an integrated theoretical perception for their practical applications. A systematic study has been conducted investigating the dependence of optoelectronic properties of solar-blind ?-Ga2O3 photodetector with varying density distribution of Ag PNPs over its surface. Interestingly, a remarkable transitions are found, where the varied distribution density of Ag PNPs changes the polarity and even reverses the traditional photodetector behaviour. According to the transient response of bare ?-Ga2O3 photodetector, device exhibit positive transient response which switches its behaviour to drastically 20 times enhanced negative transient response when decorated by sparsely placed 20 sec sputtered Ag PNPs to ?-Ga2O3 photodetector (?-Ga2O3@Ag20s). Besides, ?-Ga2O3@Ag20s device showed an incredible report-highest responsivity and EQE of 107.47 A/W, 5.35×104% respectively at 5 V for 250 nm monochromatic light on single semiconducting ?-Ga2O3-layer. In a follow-on study, by re-sputtering of Ag NPs for another 20 s (?-Ga2O3@Ag40s) the bridging of Ag interparticle gap in aggregated form results in anomalous photoconductance. Based on these facts, we construe that the charge carrier dominance process critically affected by the PNP distribution via a distinct mechanism in contrast by a conventional semiconductor-based photodetector. This opens new door for different set of applications for their admired ability to automatically switch off the system thus acting as a safe guard and other on-chip sensor. We proposed unified well-explained and systematized model and rationalize many experimental trends. Hence, our study represents the first demonstration of plasmonic tuning effect to two active dynamic switching modes; i.e. first collective report on switchable reverse and anomalous behaviour due to plasmon modulation, the fundamentals of which haven?t studied experimentally.

Resume : Multi-component ceramic coatings such as TiAlN, TiCrN, TiCrSiN and Hard carbon coatings (HCC) were used in wide range of industrial applications, as these have excellent mechanical, chemical and biological properties. These coatings were synthesized by the vapour-phase method from an arc ion plating process. PVD(Physical Vapor Deposition) coating technologies were commonly used in carrying out ceramic coatings, where the coating materials are vaporized from the source and then transported in the form of a vapour through a vacuum or plasma environment to the substrates. In recent years, 3-D printing technology has been rapidly developing and tends to apply it to the field of bioengineering such as bio-drills and artificial joints. However, the disadvantage of 3-D printing materials is that it is necessary to develop technology that can compensate for the deterioration of wear resistance characteristics. In this study, we will introduce multi-component ceramic coating technology that can complement the wear resistance characteristics of 3-D printing materials. Hard carboncoating(HCC) refers to a class of amorphous carbon coatings which is predominantly composed of the graphite-like microstructure (sp2 hybridized carbon), and has been revealed high hardness as well as unique performances for applications in protective, lubricating and biological surfaces to bio-drill for dental implantations. Comparing with most of the other amorphous carbon coatings, HCC coating fabricated by an ion-plating technique exhibited good tribological performance with low friction and low wear. It endowed the HCC coating great potential to be used as the protective and low friction working surface operated in water environment including human body. Interlayer design was important tothese performances of HCC film in water environment. The nano-interlocked microstructure formed between the substrate and carbon layer in combination with the hard strengthening carbide particles formed inside the interlayer would result in the high load-bearing capacity of HCC film coating under the sliding-friction condition in water environment.We developed successfully the bio-drills for dental implantations by using the HCC coating technologies.

Resume : Chemical Vapor Deposition (CVD) is a promising deposition method to fabricate wide range of polymers. We successfully deposited single layers of ferroelectric Polyvinylidenefluoride, Polytrifluoroethylene, and multilayer of P(VDF-TrFE) thin films using initiated CVD (iCVD) method. Chemical structure and surface characteristics are investigated using conventional characterization methods, e.g., Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy. Precise deposition of polymeric thin films, in desired chemical composition, is an ongoing challenge in organic MEMS (Micro-Electromechanical Systems) applications. In addition, charge transport in organic devices has been receiving steady attention in the past decades. Hence, as a part of a systematic study towards the microelectronic applications, we discuss electrical characterization results such as current-voltage (JV), frequency dependent loss-tangent and imaginary dielectric modulus in room temperature. Since the PVDF-TrFE copolymer thin films are not linear dielectric, ferroelectric characteristics of such thin films have applicable impacts on the experimental electrical measurement results.

Resume : Mesoporous metal oxides are frequently prepared by using porogens, either supramolecular structure directors ('soft templates') or rigid matrices ('hard templates'). Soft templates bear the advantage of being applicable to the fabrication of porous thin films or layers, though only for a limited selection of metal oxides. Furthermore, as a solution-based method, this approach is restricted to low temperature and therefore often requires post-synthetic annealing which may compromise structural integrity and porosity. These disadvantages are avoided by use of hard templates ('nanocasting'), but this is more elaborate and difficult when it comes to preparing porous films. Porogenic organic polymer hydrogels offer new opportunities as they combine the advantages from both 'soft' and 'hard' templating. We present the synthesis of mesoporous metal oxides by using poly(dimethylacrylamide) hydrogels as porogenic matrices. Porous metal oxides (e.g. Al2O3, MgO) with uniform mesopores of ca. 4 nm were obtained by swelling the hydrogels in metal nitrate solution and subsequent thermal conversion. The hydrogel forms a continuous network that takes up the inorganic precursor species with no risk of phase-separation, similar to a hard matrix. At the same time, the swollen hydrogel is highly flexible; the (cross-linked) polymer strands are more or less loosely arranged and displaceable, like a soft matrix. Porous metal oxide films with thicknesses in the µm and sub-µm range were fabricated by spreading the polymer through spin-coating, followed by photo-cross-linking and anchoring to the substrate surface. For example, homogeneous mesoporous layers of Al2O3 with large specific surface areas (up to 550 m2/g) were prepared.

Resume : Metallic nanoparticles in general are having great attention due to their huge potential in nanotechnology. Among them, Cu nanoparticles are very attractive in terms of cost when compared to Ag and Au nanoparticles. In this work we present the results of using laser ablation method in open air and in inert atmosphere to produce and deposit Cu nanoparticles on Ti substrates. The nanoparticles were synthesized by laser ablation in air at atmospheric pressure and in nitrogen atmosphere using 1064 nm radiation generated by a picosecond Nd:YVO4 laser and directly deposited on shot peening Ti substrates. The composition, topography, crystalline structure of the produced nanoparticles have been studied by energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X ray diffraction (XRD). The obtained deposits consisted of porous coatings composed of copper and copper oxide nanoparticles interconnected to form chain-like aggregates. The use of nitrogen atmosphere contributed to reduce considerable the formation Cu oxide species. The synthesized and deposited Cu nanoparticles exhibited inhibitory effect on bacteria strains.

Resume : SnO2 thin films are called as transparent conducting oxide materials according to their optical and electrical characteristics. These properties bring them as a promising candidate for optical devices. Cobalt (Co) doped SnO2 thin films were grown by spray pyrolysis method on p-type Si substrates. The cobalt doping was varied from 0 to 3 and 5 at. %. The effect of doping ratio on the optical properties of SnO2 thin films were studied. The optical reflectance of thin films was measured with UV-Vis-NIR spectrometer in the 200−2000 nm wavelength range. A complex analysis including the effect of the substrate was applied to reflectance spectrum of each film to determine the thickness more accurately. The real and imaginary parts of the complex index of refraction plus film thickness were also obtained. The optical band gap, Eg values of the films were obtained from the spectral dependence of the absorption coefficient, using the Tauc relation.

Resume : Reversible control of the wettability of solid surfaces can be achieved by stimuli-responsive polymer films. PNIPAM is a thermoresponsive polymer, which switches between hydrophilicity and hydrophobicity at 32oC. We develop thin films of blends of PNIPAM and the diblock copolymer PS-b-PNIPAM with PS (PS/PNIPAM and PS/ PS-b-PNIPAM, respectively) on flat and microstructured Si substrates and study their surface morphology and tunable wetting behavior. The morphology of the films was characterized by SEM, optical microscopy, and profilometry. Their chemical homogeneity and wetting properties were characterized by Raman spectroscopy and water contact angle measurements. Solutions of PS/PNIPAM and PS/PS-b-PNIPAM with varying ratios were spin casted on flat Si surfaces following three protocols of drying. PS/PS-b-PNIPAM films do not present a change in their wetting behavior below and above 32oC. On the other hand, the effect of tunable wettability is observed for the PS/PNIPAM films, especially those with a high ratio of PNIPAM. We observe an increase of the water contact angle up to 25o upon heating. Microstructured Si surfaces were prepared by laser processing to achieve a large specific surface area with dual-scale roughness at the micro- and nanoscale. Such substrates, either with or without the native SiO2 layer, were spin coated with PS/PNIPAM films of varying ratios. At room temperature, the micro-Si substrates provide higher water contact angles compared with the flat Si substrates. Films on micro-Si with the native SiO2 show the highest thermoresponsivity. Films on micro-Si without SiO2 show water contact angles up to 90o below 32oC and up to 110o above 32oC, becoming switchable from hydrophilic to hydrophobic upon heating.

Resume : Innovative strategies to endow osseous implants with various functionalities and smart biointerfaces able to tackle the most demanding healthcare requirements (e.g., controlled release of therapeutic ions, matching the degradation/bone growth rates, antimicrobial efficiency) are currently seek. Phosphate bio-glasses (PBGs) represent advanced biomaterials which specifically stimulate the biological responses at molecular level, successfully accomplishing the coupling of the bioactive and resorbable material designs. radio-frequency magnetron sputtered (RF-MS) PBGs have recently sparked significant interest in the biomedical field due to their ability to fully resorb in aqueous media (such as the intercellular media), with the network connectivity acting as key control parameter of their degradation speed. In this work, resorbable PBG thin films have been synthesized by RF-MS from a target with a 50-P2O5, 35-CaO, 10-Na2O and 5-Fe2O3 composition (mol%). The results indicate that the argon deposition pressure (0.2 – 1 Pa) can be used as a reliable tool to tailor the morphology, composition and structure of the films, as surveyed by ellipsometry, AFM, EDXS, and FTIR-ATR spectroscopy measurements. The possibility of fine tune the PBG films’ composition, structure and thereby biological response (e.g. in vitro degradation and cytocompatibility assays) by the sputtering pressure variable could be an important technological step in their future application as smart biointerfaces.

Resume : Novel technique of layer deposition for building asymmetric supported membranes for hydrogen separation V.A. Sadykov1,2,*, A.V. Krasnov1, Yu.E. Fedorova1, Yu.N. Bespalko1, A.I. Lukashevich1, N.F. Eremeev1, P.I. Skriabin1, O.L. Smorygo3 1 ? Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia 2 ? Novosibirsk State University, Novosibirsk, Russia 3 ? Powder Metallurgy Institute, Minsk, Republic of Belarus *Corresponding author, sadykov@catalysis.ru Design of catalytic reactors equipped with asymmetric supported membrane for hydrogen production from biofuels is important problem in modern energy field. This work aimed at developing techniques of NiCu ? Nd5.5WO11.25 ? mixed protonic-electronic conductor synthesis and its deposition on NiAl foam substrate to obtain asymmetric hydrogen separation membrane. NiCu alloy synthesis includes three steps: preparing and drying polymerized polyester precursor, pyrolysis of precursor into coked alloy nanoparticles; producing alloy nanopowder in fluidized bed reactor in H2 stream. Nd5.5WO11.25 ? (NW) was synthesized by mechanical activation of the oxides mixture. 35 wt.% NiCu ? NW nanocomposite was prepared by ultrasonic dispersion of powders in isopropanol with addition of PVB. NiCu ? NW functional layers and then 5 wt. % Ni + 1 wt. % Ru/ Sm0.15Pr0.15Ce0.35Zr0.3O2-? catalytic layers were subsequently deposited on the foam substrate by vacuum slip casting. Additional NiCu nanoparticles were deposited on the sintered in H2 layers to close residual pores. SEM with EDX was applied to characterize supported layers. Membrane testing was carried out in specially built setup. In hydrogen permeation tests a high (3 ? 5 ml H2/(cm2min) at 700 °C) hydrogen flux was demonstrated, which is provided by a high protonic conductivity of NiCu ? NW nanocomposite (~ 10 3 S/cm at 700 °C). A promising performance of this catalytic membrane was demonstrated in ethanol steam reforming reaction. Support by Russian Science Foundation (Project 16-13-00112) is gratefully acknowledged

Resume : Light-induced neural stimulation via photoactive nanocrystal interfaces faces an important challenge for the generation of retinal prostheses in terms of efficient light harvesting, required optical power and biocompatibility [1]. Recently, construction of heavy metal based graded structures offered a novel route to enhance the luminescence and photovoltaic performance of optoelectronic devices in which, non-radiative transductions of the excited state energy funnel exciton within graded structure toward the outer layer having the lowest bandgap [2,3]. Using this concept, we build an indium based fully biocompatible graded neural interface that benefits from enhanced photocurrent as a result of quantum funneling and hyperpolarized the cell membrane under illumination pulse of 50 ms. This finding can address limitations on cytoxicity and photostimulation performance of the previously reported nanocrystal based neural interfaces. [1] Bahmani Jalali, Houman, et al. "Effective neural photostimulation using indium-Based type-II quantum dots." ACS nano 12.8 (2018): 8104-8114. [2] Franzl, Thomas, et al. "Exciton recycling in graded gap nanocrystal structures." Nano Letters 4.9 (2004): 1599-1603. [3] Ruland, Andrés, et al. "Enhancing photocurrent efficiencies by resonance energy transfer in CdTe quantum dot multilayers: towards rainbow solar cells." Advanced Materials 23.39 (2011): 4573-4577.

Resume : The doping of organic semiconductors is an important tool for tuning the properties of organic field-effect transistors (OFETs). Fluorinated alkylsilanes are a group of well-studied p-type dopants, which are usually applied by sequential doping at the semiconductor-insulator interface. These silanes are deposited as a self-assembled monolayers (SAMs) on the dielectric oxide[1] or on the organic semiconductor.[2] We show an approach where the fluorinated silane is deposited on the prefabricated OFET in a bottom gate, top contact architecture. As a dopant and as a semiconductor we used mainly Trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FTS) and TIPS-pentacene, respectively.[3] A vapor- and solution-based deposition approach of the dopant were compared. For the FTS solution deposition, an orthogonal solvent, which is not dissolving the semiconductor layer during the deposition of FTS was used. Both approaches are leading to comparable results, including shifted transfer curves, increased conductivity and slightly decreased mobility. The strength of the doping effect could be controlled by the deposition time or the FTS concentration in solution. The doping effect could be further proven by Kelvin Probe Force Microscopy measurements by a negative shift in the contact potential difference. [1] Pernstich et al., J. Appl. Phys. 2004, 96, 6431. [2] Calhoun et al., Nat. Mater. 2008, 7, 84. [3] Zessin et al., ACS Appl. Mater. Interfaces 2019, 11, 2177.

Resume : Glass fiber is widely used as a reinforcing material due to its excellent strength and insulation. Many studies have been conducted to improve the mechanical properties of glass fiber-reinforced composites. One of the most effective ways to improve the properties of fiber-reinforced composites is to graft carbon nanotubes (CNTs) to the fiber surface by chemical vapor deposition (CVD) because CNT-grafted to fibers can improve the interface shear strength and electrical conductivity of their composites. However, there is a serious problem that the mechanical properties of the glass fibers can deteriorate due to the thermal decomposition when CNTs grow at a temperature of 500 ° C or higher by CVD. In this study, low-temperature grafting process of CNTs on the glass fibers is investigated using a plasma-enhanced CVD and bimetallic catalysts. The bimetallic catalyst decomposed by the plasma reactor meets the carbon source, enabling CNTs to be grown on the glass fiber surface at a low temperature. These CNT-grafted glass fibers are used to fabricate fiber-reinforced composites with epoxy matrix. The mechanical properties of the composites are characterized, focusing on the mechanism of improved tensile strength of the composites.

Resume : Transition metal carbide (MXene) have been considered as an effective EMI shielding material since EMI shielding effectiveness of MXene was published in 2016. Ti3C2 MXene film with the thickness of 10 micronmeter had over 60 dB SET due to very high electrical conductivity. MXenes are a family of 2D transition metal carbides, nitrides, and carbonitrides with the general formula Mn 1XnTx (n = 1, 2, or 3; M = transition metal, e.g. Ti, Nb, Mo; X = C and/or N; T = surface termination, e.g. ?OH, ?F, ?O). Unlike other 2D materials, MXenes offer an attractive combination of high electronic conductivity (~5000 S/cm), hydrophilicity, and processability. However, still it is lack of understanding EMI shielding behavior at the atom-scale thickness because it is hard to make uniform atom-thick film. In this presentation, we present the EMI shielding behavior of very thin MXene film with atom-level thickness. Uniform MXene thin films are prepared through self-assembly method. Thickness is controlled from monolayer- to few tens layers-thickness. It reveals that MXene is good for ultra-thin film shielding application.

Resume : Wafer level packaging (WLP) has been the mainstream of high density packaging. The reliability of copper interconnects in WLP attracts great attention. The interconnect size in WLP is decreasing meaning higher applied force formed in copper interconnects. This requires copper interconnect own superior mechanical, electrical and thermal conductive property. The copper interconnect in WLP is basically fabricated by direct current deposition due to low cost and easy fabrication of complex-shape interconnects. The property of copper interconnects, such as resistance to electromigration, soldering wettability and mechanical strength, is greatly connected with the microstructure including grain shape, crystalline orientation and twin density, while the microstructure of copper film may change significantly with the varying substrate wafers used in deposition process even though using the same electrolyte and plating parameter. Based on previous work, here we report deposition result of nanotwinned copper on different substrates commonly used in microelectronic packaging field, including wafer with titanium seed layer, titanium/gold seed layer, titanium/copper seed layer and electroless/electrodeposited Ni-P film. The nanotwinned microstructure was quite consistent from the substrate side to film surface and no transition zone at the early growth stage was found in the plated copper films. The nanoscale twins were basically parallel with the growth plane and columnar grains are vertical to the growth plane formed. It demonstrates that our optimized electrolyte (0.8M Cu2+, pH=1, 30ppm NaCl and gelatin) could produce high property nanotwinned copper film on all substrates, which means that the deposition process is quite stable, repeatable and not sensitive to the substrates we used so it could be compatible with many electrodeposition procedures in packaging process.

Resume : Accurate determination of temperature is of critical importance for an abundant number of applications therefore temperature sensors are one of the most widely used sensors in the world. An emerging demand in tomorrow’s electronics industry is that of printed flexible and stretchable devices1. The prospect of developing flexible printed sensors over large areas opens up new applications such as low-cost sensing devices. In this work we report on a class of thermistors made up of ceramics well known for their temperature dependences, such as MnNiOx, used as temperature sensors since they show reproducible and large negative temperature coefficients (NTCs).The thermistors we developed have proved suitable for obtaining printed temperature sensors exhibiting a stability sufficient enough to determine the temperature within 0.1°C. The sensors are based on ceramic-polymer composites demonstrating a sensitivity as high as 4% of resistivity change per degree Celsius. However, a draw back for the application of these sensors on flexible substrates is that their fabrication temperature is in excess of 300°C. The ceramic-polymer composites we have developed overcome this hurdle and based on careful structural and electrical characterization we report on critical device geometry parameters that unveil the relation between the sensor performance and the polymer binder. Acknowledgements: Part of this work was financially supported by the Stavros Niarchos Foundation within the framework of the project ARCHERS (“Advancing Young Researchers’ Human Capital in Cutting Edge Technologies in the Preservation of Cultural Heritage and the Tackling of Societal Challenges”) 1. M. Schubert, C. Münch, S. Schuurman, V. Poulain , J. Kita and R. Moos, Sensors 2018, 18(11), 3982; doi:10.3390/s18113982

Resume : Organic photodiodes, (OPDs) based on organic semiconductors with high absorption coefficients for visible light, are emerging as potential candidates for replacing silicon photodiodes in image sensors, particularly due to the possibility of realizing a thin thickness and exclusion of color filters, both of which can contribute to a dramatically enhanced degree of integration for image sensors. To realize such a goal, here we introduce two new approaches for realizing color selective, thin film and high detectivity OPDs. The first approach is employing Schottky junction for exciton separation instead of conventional p-n heterojunction, so that the absorption spectrum of a single organic semiconductor component can be fully reflected the resulting detectivity spectrum of OPD. With the strategical idealization of Schottky OPD, we demonstrate an unprecedentedly high specific detectivity of 2.4×10^13 Jones with exceptional reliability and stability. The second approach is introducing a new dual-function “etalon-electrode”, which can perform the function of an electrode, and simultaneously the function of selective wavelength transparency. A strategically designed OPD architecture consisting of an etalon-electrode, a panchromatic organic active layer, and a counter electrode displays well-defined narrowband (full width at half maximum <100 nm) R-/G-/B-selective detectivity spectra with high detectivity values over 10^12 Jones.

Resume : Smart polymers react to multiple external stimuli (e.g., temperature, pH) by taking up water from the environment or repelling it out again. This reversible swelling behavior is particularly interesting for application in sensors and actuators. As water diffusivity is the time-limiting step during swelling, the use of thin films is crucial for achieving fast response times. In this study, water-stable and temperature-responsive cross-linked poly(N-vinylcaprolactam) (pNVCL) thin films were synthesized by initiated chemical vapor deposition for the first time. Effects of deposition parameters (e.g., flow rates of chemicals, filament temperature) on the temperature-responsive behavior of the thin films are investigated. The polymer undergoes a phase transition between a “hydrophilic” swollen state to a “hydrophobic” shrunken state below and above the lower critical solution temperature (LCST), respectively. This transition is investigated by spectroscopic ellipsometry as temperature-dependent swelling. As already shown for other polymers, also the investigated pNVCL systems can be tuned in terms of maximum swelling (5-200% of dry thickness) and LCST (20-40°C) via cross-linking. Additionally, the newly developed systems exhibit a filament-temperature-dependent swelling behavior, which to the authors’ knowledge is reported for the first time. Together with the biocompatibility reported for pNVCL, this characteristic makes it promising for biomedical and environmental applications.

Resume : Crystal phase-controlled synthesis of noble metal nanocrystals is increasingly desired, as crystal phase can significantly affect their physicochemical properties and potential applications in photovoltaics, catalysis and electronics.[1-5] Recently, our group have reported a novel crystal phase in Au nanoribbons (NRBs), the hexagonal 4H crystal phase, via a facile colloidal synthesis.[6] By using the 4H Au NRBs as templates, a series of 4H metals including monometallic nanostructures (e.g. Ag, Pt, Pd, Ru, Rh, Ir, Os, and Cu) and alloys (e.g. PtAg, PdAg, and PtPdAg) have been successfully prepared via the epitaxial growth method.[7] These reports offer a general and efficient strategy to prepare metal nanostructures with unusual 4H crystal phase, enabling the further investigation on the phase-dependent physicochemical properties.

Resume : We used a two-zone chemical vapor deposition (CVD) to grow the large-scale monolayer MoS2 based on solid-phase precursors, including MoO3 and S. The as-grown MoS2 is characterized using (1) Raman spectrometer to initially realize the monolayer behavior of samples based on the different frequency of in-plane (E12g) and out-of-plane (A1g ) optical vibration of S; (2) scanning electron microscope (SEM) and (3) atomic force microscope (AFM) to clarify the large scale atomic thick morphologies of samples. MoS2 has been also known as a low cost, good stability, high catalytic activities material to alternative Pt has paid much effort in field of nanotechnology and nanomaterial. Thus, we employed the as-synthesized monolayer MoS2 for investigating the hydrogen evolution reaction (HER) of sample, and studying the improvement of HER performance by electrochemical treatment. The electrochemical treatment of MoS2 was done by applied a constant current density of 1 mA/cm2 for 60 min and the comparison of HER was characterized with linear sweep voltammetry (LSV) using an Ivium electrochemical station. This simple and highly effective approach steps toward the fabrication of commercial MoS2 to alternative Pt in hydrogen production. This research was supported by the Nano•Material Technology Development Programthrough the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (2016M3A7B4904328).

Resume : The fabrication of semiconducting film by electrodeposition has a high commercial interest because it is a potentially cheap deposition technology, which would enable thin-film to become more prices competitive. In addition, to have highly efficient semiconducting devices a careful control on the electrodeposition process and the presence of dopants or impurities is of critical importance to the final properties of a semiconductor. The impurities incorporated into the deposits can come from high purity reagents. An increase of up to 2.5 times in the power factor is obtained just by using different high purity Te reagents from different suppliers. These results demonstrate that the incorporation of trace impurities from the Bi2Te3 electrochemical bath play an important role in the thermoelectric properties of the film. To make that observation, bismuth telluride (Bi2Te3) films were electrodeposited under the same conditions, but using three different Te powder sources. All the powders tested have a nominal purity equal to or higher than 99.99%. In all the cases, we could achieve films with highly oriented along [110] direction, with the same 2 to 3 Bi/Te ratio, and similar surface, and cross-sectional morphology. However, the thermoelectric properties (electrical conductivity, Seebeck coefficient, and thermal conductivity) depending strongly on the different tellurium powders sources used. Spectrometry of mass with coupling inductive measurements were performed to know which elements influence the final thermoelectric properties of Bi2Te3 films[1, 2]. References 1. Manzano, C.V., et al., Thermoelectric properties of Bi2Te3 films by constant and pulsed electrodeposition. Journal of Solid State Electrochemistry, 2013. 17(7): p. 2071-2078. 2. Manzano, C.V., B. Abad, and M. Martín-González, The Effect of Electrolyte Impurities on the Thermoelectric Properties of Electrodeposited Bi2Te3 Films. Journal of The Electrochemical Society, 2018. 165(14): p. D768-D773.

Resume : Autoimmune disorder is a kind of common chronic disease, which is difficult to cure throughout life. Small chemical drugs such as glucocorticoids, immunosuppressors and non-steroidal anti-inflammatory drugs have been widely used for the treatment of autoimmune disorders. However, these small chemical drugs suffer from poor solubility, short circulating half-life and adverse side effects, which lead to poor compliance to patients and limit the widely clinical use. One of the most effective strategies to extend the circulating time is loading drugs into nanocarriers to form nanomedicines, which is of particular interest for cancer and viral diseases therapy but seldom applied in autoimmune disorder treatment. Furthermore, current carriers have many drawbacks such as poor biocompatibility, low stability and over-complicated design. In this study, we developed an easy but general drug delivery platform based on the new polyhydroxyalkanoate terpolymer-poly(3- hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBVHHx). We reported the first example of PHBVHHx nanoparticle loaded non-steroidal anti-inflammatory drug, ultimately being applied in systemic lupus erythematosus therapy. These nanoparticle are biodegradable, stable, and show improved pharmacokinetics, optimized biodistribution, low systemic toxicity and excellent in vivo therapeutic efficacy in a MLR/lpr murine model of systemic lupus erythematosus. This delivery system may provide a new and general platform for the development of nanomedicines with enhanced therapeutic efficacy and reduced side effects.

Resume : While paints are applied to beautify and protect surfaces of structures, these coated surfaces are frequently exposed to varying weather conditions leading to degradation. Nanomaterials such as silver nanoparticles (AgNPs) can be embedded to minimize the degradation rate. This study examined the influence of AgNPs on some selected physical and mechanical properties of emulsion paint. AgNPs were prepared from cobwebs via green synthesis. In each of the paint samples, 0.35 wt% of combined AgNPs and biocide acticide (Benzimidazole Carbamate, EPW) was added to paint components including additives, and the mixtures were mixed with deionized water to obtain a litre of emulsion paint. Aside EPW and AgNPs that were varied, other components were kept constant. The concentrations of AgNPs were 0, 0.15, 0.175, 0.20 and 0.35 wt%. The AgNPs embedded paint samples were then characterized structurally for crystalline information, surface morphology, particle size and elemental composition. The physico-mechanical properties such as viscosity, specific gravity, hiding power, abrasion strength and environmental degradation rate at 300 days were examined. FTIR spectra confirmed the functional groups of the solvent, extender/fillers, pigment, binder and additives of the samples. Similarly, the XRD pattern revealed the presence of diffraction peaks corresponding to hexagonal and cubic shapes of AgNPs, tetragonal shape of titanium dioxide and hexagonal shape of calcium carbonates for modified paint samples. The EDX results confirms the presence of Ca, C, O and Mg, as the dominant elements while SEM images show that the elemental particles of the paint are largely spherical with particle size distribution in the range of 90-1200 nm. Compared to the paint without AgNPs, the paint containing equal mixture (0.175 wt%) of AgNPs and EPW gave the optimal mix for all physico-mechanical properties tested. In this case, the specific gravity was reduced by 16%, the hiding power/opacity was increased by 30% while the abrasion strength was enhanced by 236% or 3.5 folds. However, weathering and natural exposure test did not show significant change over the 300 days of monitoring. These results indicate that AgNPs significantly improve mechanical properties of emulsion paint.

Resume : In the last decade, optogenetic approaches have been successfully utilized to explore numerous neural states and disorders. While it has facilitated novel investigations that were previously infeasible, the efficient optogenetic manipulation of neural activity is contingent on delivering a sufficient dose of light to the target neuronal cells. Prevailing strategies including inducing a optode light delivering device limits the application of optogenetic engineering. Due the ability of penetrating tissue by near-infrared (NIR), upconversion nanoparticles (UCNPs) possessing emitting high energy of visible light upon excitation with low-energy NIR light are commonly used in optogenetic technology. In this study, we proposed an all-optical method for tetherless remote control of neuronal activity using an implantable hybrid scaffold constructed by a nanostructured gold inverse opal (NGIO) embedded with UCNPs, and a PDMS matrix as package. Because of the enhanced plasmon effect by the unique flower-like nanostructure and inverse opal microstructure, the 475 nm light emission excited by NIR is substantially enhanced approximately 3000 times compared to the gold plate film. Material characterizations, local field electrical stimulation, in-vitro and in-vivo experiments are systematically validated. The newly-designed implantable NGIO membrane extends the application for wireless optogenetic electronics.

Resume : We have employed ab initio molecular dynamics simulations to study the oxidation behavior of TiAlN hard coatings as a function of Al content and temperature. Results show that for TiAlN with a low Al content (Ti0.75Al0.25N), Ti atoms can always bond with O atoms, while Al atoms bond with O only at a higher temperature. For Ti0.5Al0.5N, both Al and Ti can bond with O atoms, irrespective of temperature. Through analyzing the displacement height of O-bonded metal atoms, we suggest that titanium oxide nucleates at the outermost layer of Ti0.75Al0.25N while the outermost layer after Ti0.5Al0.5N is exposed to oxygen is aluminum oxide. Our simulation results predict that Ti0.5Al0.5N has superior oxidation resistance in comparison with Ti0.75Al0.25N. In addition, we further studied the oxidation behavior of TiAlN alloyed with metallic elements, thus altering the oxidation properties. This study provides an atomistic insight to the initial stage of the oxidation process, which is else difficult to observe experimentally

Resume : New transition metal nitride compounds are explored using a combination of epitaxial layer growth, first-principles calculations, and measurements of electronic, optical, and mechanical properties as a function of composition and structure. Rock-salt phase nitrides are both mechanically and thermodynamically stable for group 3 transition metals. However, increasing the valence electron concentration by moving towards the right in the periodic table increases the strength of metal-metal bonds leading to a brittle-to-ductile transition and enhanced toughness, but also decreases the formation energy of vacancies on both cation and anion sublattices, resulting in vacancy-stabilized compounds like cubic WN with a dramatically reduced elastic modulus, and new thermodynamically stable phases like a 5-fold coordinated base-centered monoclinic stoichiometric MoN. Transition metal nitrides with a vanishing density of states at the Fermi level are semiconductors with promising properties for high-temperature electronic, thermoelectric, opto-electric, piezo-electric, plasmonic and magnetoresistive devices. Examples include ScN with a 0.92 eV bandgap and a carrier concentration which is controlled by F doping, CrN which is a Mott-Hubbard type insulator with a 0.2+/-0.4 eV gap and structural and magnetic phase transitions at 280 K, wurtzite structure Al1-xScxN which exhibits a structural instability with a non-linear bond angle composition dependence, and Ti0.5Mg0.5N with a 0.7-1.7 eV indirect gap.

Resume : Scandium nitride is of interest for thermoelectric applications due to its high Seebeck coefficient (1). Theoretical studies show (2,3) the possibility of synthesizing a ternary nitride that shares the electronic structure of ScN by replacing scandium with a group 2 alkaline earth and group 4 transition metal. Using density functional theory (DFT) calculations the phase stability and semiconducting properties of trigonal (NaCrS2 prototype, R -3 m H) TiMgN2 is predicted. In this study we synthesized (Ti,Mg)N thin films by magnetron sputtering. The films were deposited onto sapphire substrates at 400 °C (25 sccm/65 sccm N2/Ar gas flow), keeping the gas pressure at 0.65 Pa. Characterization by θ-2θ X-ray diffraction (XRD) and pole figures shows rock-salt cubic growth. 4-point-probe measurements show an electrical resistivity of 150 mΩcm. In addition, we aim to anneal the (Ti,Mg)N films in pure nitrogen in order to study the formation of the NaCrS2 superstructure. References [1] P. Eklund, S. Kerdsongpanya and B. Alling: J. Mater. Chem. C, (2016) 4, 3905 - 3914 [2] M. A. Gharavi, R. Armiento, B. Alling and P. Eklund: J. Mater. Sci., (2018) 53, 4294 – 4305 [3] Y. Irokawa and M. Usami: Jpn. J. Appl. Phys. (2016) 55, 098001

Resume : Transition-metal (TM) diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications because hardness is usually accompanied by brittleness. Toughness, which is the combination of hardness and ductility, is required to avoid brittle fracture. We demonstrate a strategy for increasing both the hardness and the ductility of ZrB2 thin films, selected as a model TM diboride, grown by hybrid high-power impulse and dc magnetron (HiPIMS/DCMS) co-sputtering in pure Ar at 450 °C on Al2O3 (0001). A Ta target operated in HiPIMS mode supplies energetic Ta ions to the growing film, while a compound ZrB2 target operated in DCMS mode provides a continuous flux of Zr and B atoms. A substrate bias of 100 V is synchronized to metal-rich portions of HiPIMS pulses. The average power applied to the HiPIMS Ta target, and the HiPIMS pulse frequency, are varied from 0 W to 600 W (100 Hz), 1200 W (200 Hz), and 1800 W (300 Hz); the other deposition parameters are maintained constant. The resulting boron-to-metal ratio, y = B/(Zr + Ta), in Zr1-xTaxBy films continuously decreases from 2.4 to 1.5 as the power is increased, whereas x increases from 0 to 0.3. A combination of XTEM, analytical Z-contrast STEM, EELS, EDX, and XRD analyses, reveal that all films have the AlB2 hexagonal crystal structure with a columnar microstructure. Films with x < 0.2 have B-rich boundaries, while those with x ≥ 0.2 have Ta-rich column boundaries. This microstructural transition results in an increase in hardness from 35 to 42 GPa, ~20%, with a simultaneous increase in the nanoindentation toughness from 4 to 5.2 MPa√m, ~30%.

Resume : Future tasks in many different fields of academia and industry are directed towards environmental sustainability, asking also for new advance in the field of protective coatings. Especially, transition metal diboride based films exhibit a great potential to be applied in various applications because of their excellent thermal and chemical stability, high hardness as well as electrical conductivity. Latest studies on diborides showed that this material class prefers to crystallize in two related hexagonal crystal structures: α-AlB2 or ω-W2B5-x prototype, respectively. In a previous ab initio study, we proposed single phased α-W1-xTaxB2 as a material system where the addition of Ta promises to only slightly decrease the excellent mechanical properties (e.g. ductile behavior of α-WB2) by simultaneously increasing its phase stability. For an experimental validation of these predictions, we deposited the full compositional range of W1-xTaxB2 thin films using magnetron sputtering. On behalf of structural investigations, we could confirm that single phased structured α-W1-xTaxB2 thin films are formed up to Ta contents of 26 at.%. These films were investigated by nanoindentation and in-situ micromechanical bending tests to evaluate the mechanical properties. Based on our results, we can conclude that the experimental investigations are in excellent agreement to the theoretical predictions and the fracture toughness decreases with increasing Ta content only from 3.7 to 3.0 MPa√m.

Resume : Diamond-like carbon (DLC) coatings are widely used because of their excellent mechanical, electrical and optical properties. Hydrogen-free DLC with high thermal stability deposited by physical vapour deposition, however, suffer from high internal stresses. In this contribution, DLC coatings deposited by High Power Impulse Magnetron Sputtering (HiPIMS) are presented. There are two possible approaches to increase C ionization in sputtering, either by using Ne as the process gas, or by increasing the discharge current to achieve a discharge runaway. With sufficiently high C ionization, dense DLC films can be deposited by either approach. Such films are free from the common columnar microstructure with hardness about 25 GPa and moderate internal stresses of about 2.5 GPa. When deposited on steel substrates with a suitable interlayer, a large improvement in the tribological performance is achieved. The wear rate measured by pin on disk was 2×10-17 m3/Nm, an order of magnitude lower than the corresponding DLC deposited without enhanced ionization. The work was supported by M-ERA.Net project TANDEM through Vinnova, FCT–Fundação para a Ciência e a Tecnologia (M-ERANET/0003/2015), and UEFISCDI, project No 56,57/2016.

Resume : CoCrMoC/a-C:H coatings have been designed and deposited on medical CoCrMo (ISO 5832-12) alloy substrates by reactive magnetron sputtering from targets of the same alloy in the C2H2/Ar atmosphere. Their structure evolution with an increasing carbon content as well as chemical and phase composition were investigated by x-ray diffraction, x-ray photoelectron spectroscopy, and transmission electron microscopy. Results show that microstructure of deposits evolves from biphasic, containing (fcc) and (hcp) metallic phases for low carbon content, through nanocrystalline and amorphous for carbon content between 10 and 20 at.%, to quasi-amorphous nanostructural for even higher content of carbon. Segregation of amorphous carbon leads to the formation of selforganized tubular nanostructure for coatings containing more than 30 at.% of carbon. Studies of mechanical and tribological properties revealed that introduction of carbon into CoCrMo alloy results in significant increase of hardness and improvement of load-bearing capacity. Compared to uncoated CoCrMo substrate, deposited coatings with high carbon content exhibited superior tribological properties with lower friction coefficient and wear rate. Simultaneously, corrosion resistance studies, performed by means of potentiodynamic polarization tests and electrochemical impedance spectroscopy, showed high chemical inertness of nanostructural coatings in simulated body fluid (Hank’s balanced salt solution).

Resume : High-power impulse magnetron sputtering (HiPIMS) is a very suitable and progressive method for preparing high-quality oxide layers. Enhanced energy of target material ions impacted onto the growing film could substitute thermal heating of the substrate which is very important in the case of deposition on a heat sensitive substrates. In spite of this fact, the use of reactive HiPIMS for the preparation of In-Ga-Zn-O (IGZO) and Al-doped ZnO (AZO) layers has been rarely reported only. In this paper we show the use of reactive HiPIMS is an effective way to produce IGZO and AZO layers. Optical emission spectroscopy (OES) of the plasma discharge was also carried out. OES shows the qualitatively changes in particles fluxes composition to the substrate under different conditions. Difference in oxygen transport mechanism for deposition with metallic (AZO) and ceramic (IGZO) target will be also discussed.

Resume : Au-Co nanocoupling finds interesting applications in catalysis, sensing and magneto-plasmonics [1,2]. The intrinsic alloy instability usually leads to a partial segregation of the two metals that hinders a detailed analysis of the alloy structure, from which the technologically-relevant properties depend. Here we shed new light on the structure of bulk-immiscible Au-Co nanoalloy, produced by coupling room-temperature physical vapor deposition with nanosphere lithography. The results based on short- and long-range order structural investigations as X-ray Absorption Spectroscopy (XAS), X-Ray Diffraction (XRD) and Diffraction Anomalous Fine Structure (DAFS), show that the alloy is amorphous, coexisting with a minor fraction of AuxCo1-x nanocrystals. The amorphous fraction is related to the different atomic radii of the two metals, combined with the limited diffusivity of the deposition process. The alloy induces a net magnetic moment of Au atoms, as measured by X-ray Magnetic Circular Dichroism (XMCD). The structure of the crystalline fraction (crystal size and orientation) depends on the specific produced nanopattern. The alloy thermal stability is also discussed. These results are expected to help to correlate the atomic structure of the Au-Co nanoalloys with their technologically relevant properties.

Resume : This is a study of Au, Ag and Au-Ag nanostructured surfaces used as SERS substrates for in vivo label free diagnosis in oncologic surgery. A particularly interesting and also feasible way of reducing the acquisition times of spectra without diminishing the accuracy of the diagnostic is surface enhanced Raman scattering (SERS). Metal nanostructures provide up to 1012 signal intensity amplification due to the resonant interaction of light with the surface plasmons excited at the surface of the structure. The spectral resolution increases and the time required to collect the spectra is significantly reduced. We have adopted different techniques to create the nanostructures on surgical-grade stainless steel surfaces e.g. magnetron sputtering and direct imprint using a net-like pattern and Au/Ag nanoparticle solutions cyanide free with various concentrations. The coatings underwent an appropriate postdeposition annealing to enhance adhesion and allow for typical temperature sterilization processes. The surfaces roughness lays between 3 and 11nm depending on the material and deposition process. Surface analyses by SEM, AFM, confocal microscopy have shown uniform distribution of the nanostructures and uniform roughness over the coated surfaces. A study of the performance of the nanostructured surfaces in terms of enhancement of the Raman signal shows that Ag provides the highest amplification, followed by the Au-Ag alloy and Au. Aging within short whiles diminishes drastically the SERS effect of the Ag coatings whereas Au-Ag ones preserve their performance over very long intervals. The coatings have been tested in real conditions and show that label free SERS with 632nm Raman excitation can provide fluorescence-free spectra of fresh samples when the nanostructured blades are employed. Screening of body fluids in general and with SERS in particular may represent a strategic target for direct ex-vivo diagnostics in mammary surgery, skin cancers and other diagnostic applications. Acknowledgements: Core Program PN-2019-OPTRONICA VI.; Institutional Performance Programme 2019

Resume : In the last decade, nanoparticles (NPs) have attracted a lot of attention because of their unusual characteristics when compared to bulk material, such as reactivity, antibacterial, optical and magnetic properties among others. In this study, ZnFe bimetallic NPs and AgAu bimetallic NPs were produced by plasma gas condensation process onto carbon substrates to exploit the galvanic couple formed for such dissimilar metals. ZnFe NPs are expected to provide oxygen scavenging promoted by galvanic corrosion properties for food packaging applications; while AgAu NPs are expected to form a galvanic pair promoting the Ag release to incorporate in carbon matrix for biomaterials applications, namely ureteral stents with the purpose of reducing microbial encrustation. The bimetallic NPs were produced by plasma gas condensation process consisting in a gas aggregation cluster source connected to the main deposition chamber of a magnetron sputtering equipment. In the case of ZnFe NPs production, a Fe (99.5 %) target with an area of 2000 mm2 was connected to the magnetron head of cluster source. In the deposition chamber, a Zn (99.99%) target with 100 × 200 mm2 was connected. For the production of AgAu NPs, an Ag (99.99%) target modified with Au pellets (99.99%) with an area of 2000 mm2 was connected to the magnetron head. All depositions were performed in Ar atmosphere. The structure, morphology and composition of the NPs were determined using both a JEOL 2100F TEM and an FEI Titan-ChemiSTEM. STEM/EDX elemental maps were used to evaluate the evolution of ZnFe NPs oxidation as a function of time and relative humidity (RH) and to AgAu NPs were used to evaluate the distribution of Ag related with Au. The results demonstrate that for ZnFe NPs produced by gas agglomeration system, the oxidation is potentiated, showing a higher dissolution rate compared to ZnFe nanoalloys created by conventional magnetron sputtering. These results demonstrate the possibility of controlling the oxidation/dissolution of the nanoparticles, which may regulate the oxygen scavenger capabilities and the migration of the nanoparticles. For AgAu NPs, the results shown a shell formed by silver on the gold. Some particles also show the formation of Ag satellites on the gold which can promote the oxidation of Ag and thus become an antimicrobial agent.

Resume : In this research, we report deep ultraviolet (DUV) light-assisted crystallization of amorphous TiO2 films and their applications to energy conversion devices. Amorphous TiO2 films deposited by atomic-layer-deposition were irradiated with DUV light under nitrogen atmosphere while the substrate temperature was maintained at the temperature between 150 and 400oC. Various film characterizations confirmed that DUV irradiation substantially accelerates the nucleation rate and reduces the minimum temperature for crystallization (anatase) of amorphous TiO2 film by 100 degrees compared with thermal annealing without DUV irradiation. Furthermore, it was demonstrated that the DUV photoactivation with concurrent thermal annealing induces the formation of unconventional brookite phase and preferential facet orientation, which was never reported in the previous literature. Finally, the DUV-assisted low-temperature crystallization was successfully employed to form high-quality anatase films regardless of substrates, for high-performance photoelectrochemical cells and perovskite photovoltaics. Our results suggest that DUV photoactivation can provide a low-temperature post-treatment to form metal oxide films with well-defined crystallinity and preferred phase orientation on unconventional substrates.

Resume : Low-temperature solid oxide fuel cell (LT-SOFC), operated at a temperature of 500℃ or below, is attracting attention as a next-generation energy conversion device due to advantages such as high energy conversion efficiency, environment friendliness, and ease of application to portable devices. However, the performance of LT-SOFC decreases mainly due to sluggish oxygen reduction reaction (ORR) at the cathode at low operation temperature. This problem can be solved by using platinum group materials (PGMs) having high catalytic reactivity as electrode materials. However, PGMs are thermally unstable due to their high surface energy. Therefore, it is essential to develop an electrode structure that is thermally stable and has a high catalytic reactivity to fabricate a high performance fuel cell. In this study, we designed and fabricated high performance and durable electrodes by overcoating an ultra-thin CeO2 layer using atomic layer deposition (ALD) on the Pt cathode surface. The optimized Pt-CeO2 electrode structure in the bulk electrolyte based system was designed and tested. The cell with CeO2 coated electrode (5 ALD cycles, ~ 2 nm thick) shows a 70% lower activation resistance than the cell with Pt-only electrode. It also showed higher thermal stability by a factor of 2 compared with the cell with Pt-only cathode. In addition, when applied to thin film SOFC based on anodized aluminum oxide (AAO) substrate, the cell showed a high performance of 800 mW/cm2 at the operating temperature of 500 ℃, which is the highest performance at the same temperature among the AAO-based studies published previously. Acknowledgements We thank Dr. Wontae Noh and Air Liquide Laboratory Korea for providing Ce precursors.

Resume : An important problem of science and technology is to ensure the reliability and durability of machines parts and tools by hardening the of products surface layer. Electric-spark alloying (ESA) and ion-plasma nitriding (IPN) are perspective high-energy methods of coating creation. In these methods, using the concentrated fluxes of electric energy, the chemical composition of the surface layer, the structural-phase state and properties are changed. Extreme conditions of the ESA process provide an opportunity to obtain nanostructures in the coating. The purpose of this work is to investigate the effect of the ESA and IPN processing sequence, and sequence of alloying elements (Fe - Cr - Ti) applying on the structure, phase composition and microhardness of the steel surface layers. It was established that after complex processing coatings are formed, the peculiarity of which is the presence of two hardened layers with different characteristics: thin layer (up to 20 ?m), which alloyed by Fe, Cr, Ti with microhardness 8 - 11 GPa and nitrided sublayer (length 40-160 ?m) with a microhardness of 4,5 - 7 GPa. It has been shown that in complex processing in the IPN + ESA sequence, the microhardness of the hardened zone of steel AISI 420 is higher (11.1 GPa), and the length is greater (160 ?m) than ESA + IPN sequence (8.5 GPa and 40 ?m respectively). It was found that alloying at the last stage by nitride-forming elements - Cr or Ti results in higher values of the surface layer microhardness than alloying by Fe, which is caused by the formation of nitride phases. Results obtained in the work and the established patterns of structure formation and properties of the alloyed layers after the process ESA can be used to extend the life of machines parts and mechanisms working in hard conditions.

Resume : Plasma immersion ion implantation and deposition method is realized when high-voltage pulse bias potential is applied to the substrate. A thermodynamic approach based on the concept of nonlocal thermoelastic peaks (NTP), which are generated by implanted ions is used to explain the known experimental regularities of structure formation and stress state in coatings. A theoretical analysis of the synthesis of metal nitride coatings with the cubic NaCl-type structure is provided. The radius, the depth of the accumulation and the temperature in the peaks are determined, depending on the energy that the ions acquire under the action of the accelerating potential. The structure and compressive stress level in the coatings are considered together, as a result of the competition between two differently directed processes in the NTP: radiation-induced defects formation and their removal due to thermal migration. It is supposed that the result of competition provides a minimum of free energy of the synthesized coating. Relaxation processes in coatings associated with decrease of stress and change of tex-ture from [111] to [110] or [100] are activated when the peaks temperature exceeds 1/3 of the melting point.

Resume : The Co-Cr alloys are widely used in the field of the modern medicine and have a large number of biomedical applications, such as manufacturing of dental, joint implants, etc. due to their excellent mechanical properties, corrosion resistance and biocompatibility. However, some drawbacks related to the poor wear resistance can be mentioned which causes a formation of debris leading to inflammation of tissues and aseptic loosening of joints. The discussed limitation depends mostly on the surface properties of the Co-Cr alloy and can be overcome with an appropriate technology for surface manufacturing. In this work, the effect of the electron-beam surface treatment (EBST) of Co-Cr alloys using continuous electron beam was studied. The technological parameters, namely accelerating voltage (U) = 60 kV, beam current (Ib) = 15-30 mA, speed of the specimen motion (V)=0.5-5 cm/sec, scanning frequency (f) – up to 10 kHz. The technological conditions of the electron-beam process were systematically varied. The obtained samples were characterized in terms of their microstructure and crystallographic structure by Scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The tribological properties of the obtained specimens were discussed with respect to the applied technological conditions of the EBST and corresponding microstructure and crystallographic structure.

Resume : The impact of crystalline phase evolution on emitting properties of Nd-doped Si-rich HfO2 films obtained by RF magnetron sputtering has been investigated by means of scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman scattering and photoluminescence (PL) techniques. It was observed that thermal treatment of the films at 950-1100°C governs a phase separation process. The formation of tetragonal HfO2 nanocrystals along with the Si quantum dots (QDs) occurs at 950°C. Higher annealing temperature stimulates the formation of monoclinic HfO2 nanocrystals accompanied by the oxidation of Si QDs and appearance of tetragonal SiO2 nanocrystals. The PL emission related to the optical transitions in the 4f intrashell of Nd3+ ions has been detected. Its enhancement was observed for the films annealed at 950-1000°C due to an effective energy transfer from Si QDs towards the Nd3+ ions. The oxidation of Si-QDs upon the annealing at higher temperatures (up to 1100°C) results in the quenching of the Nd3+ PL emission. Since hafnia-based materials have high density and are very sensitive to high-energy excitation, the results reported here offer the application of doped hafnia films as luminescent materials for traditional phosphors.

Resume : Two-dimensional (2D) materials made of transition metal ditellurides (TMDC) have been studied intensively because their physical properties are found to vary depending on their geometry. Some of TMCD materials exhibit metallic behavior. Also, they can be transparent once they are in the form of a thin layer. Sputtering technique is one of the most reliable method to fabricate thin films because the technique guarantees reproducibility and thus it is currently utilized for mass production. Here, we attempt to fabricate thin films of nickel ditelluride with two sputtering methods: sputtering from NiTe2 intermetallic target and from Ni and Te targets, co-sputtering). Both of fabricated thin film crystal structure is NiTe2, Melonite. Our results prove that nickel ditelluride are one of promising candidates for transparent electrodes compared to existing electrodes, resistivity of about 200 μΩcm and transparency of > 80%. First, 2 inch-compound targets were prepared by fabricating the intermetallic followed by SPS. We controlled sputtering power and deposition time and substrate heating conditions to maximize their electrical conductivity. Through TEM analysis proved that more grains were aligned with c-axis, basal plane of hexagonal structure. The thickness of the thin film reduced by chemical exfoliation.

Resume : This research presents the results on the synthesis of ZnSe nanocrystals in а-SiO2/Si track template. The structure of а-SiO2/Si was prepared by thermal oxidation of Si substrate (n or p- type) . The thickness of SiO2 layer was 700 nm. The structures were irradiated at a DC-60 accelerator (Astana) with 200-MeV Xe ions, Φ=108 ions/cm2. Chemical etching of irradiated samples was produced in HF solution. Electrochemical deposition (ECD) in track template was carried out at a voltage range (1 - 1.25) V, t=10 - 15 min. For ECD ZnSe, the following electrolyte was used: (Zn – 7.2g/ml, SeO2 – 0.2g/ml). The surface of the precipitated samples was examined using SEM JSM 7500F. XRD patterns were obtained using the X-ray diffractometer D8 ADVANCE ECO. The main phase for all samples is amorphous, it dominates over the crystalline one. Annealing in air at 300 ° C leads to an increase in the degree of crystallinity. The unit cell parameters are almost the same for all samples. Annealing also leads to an increase in the size of nanocrystallites. Thus, ZnSe nanocrystals were first obtained by synthesis into a- SiO2 / Si track templates.

Resume : High entropy alloy (HEA) thin films have attracted research interest because of simple structure, slow diffusion, good corrosion resistance and, rendering them a great potential as high temperature structural materials for different applications. Thus, it is a critical issue studying their structural stability during high temperature annealing. The aim of the present work is growing CrFeCoNiCu HEA thin films of 50 nm thickness andannealing them in-situ in the electron microscope for a better understanding and controlling the early stages of phase instability of as deposited films at temperatures up to 550 oC. The as deposited CrFeCoNiCu alloy films havesingle phase fcc structure and a grain size of about 10nm. No changes in their structureare detected up to 400oC. Separation of components is observed at 450 oC,where both the appearance of a bcc phase with a lattice parameter of 0.30 nm is registered as well as grain growth starts. Grains of 100 nm in size are forming in which the deviation from originally present equiatomic composition is measured by elemental mapping in STEM.Chemical separation and grain size growth as a function of time at 450 oC is presented.

Resume : In the context of resonant gratings applications, the ability to easily switch the resonance on and off is a key to numerous new developments. Thus, a thermally activated resonant grating may be used as an innovative passive Q-switching self-protecting device for high power lasers in the infrared domain. Such a design can rely on VO2’s thermochromic properties in the infrared, transiting from a transparent dielectric at room temperature to an absorbent insulator at temperature as low as 70 °C. Here, 25 to 50 nm thin VO2 films are synthesized on fused silica by KrF Pulsed-Laser Deposition in oxygen using a metallic vanadium target, followed by annealing in a Rapid Thermal Processor reaching temperatures of 500 °C. Combined with a high refractive layer such as TiO2 and a periodic corrugation (grating), the structure acts as a resonant waveguide grating which resonance in reflection for TE polarization in normal incidence reaches more than 60 % in the NIR range. The bi-layer VO2/TiO2 is considered as a homogenous waveguide with low losses since refractive indexes are very closed in the dielectric behavior of the VO2 (“gold”). The excitation of the waveguide mode is performed with a photoresist based grating leading to a high reflection for one polarization and one wavelength. The preliminary results show a thermally controlled resonance reflection leading from 50% reflection to less than 5% when the structure is heated due to the metallic lossy behavior of the VO2 layer.

Resume : High entropy alloys (HEAs) have several excellent properties such as good resistance to high-temperature oxidation, wear, radiation, and corrosion. Many important applications, where these properties are exploited, require thin films deposited on various substrates. Since HEAs contain at least 5 different chemical elements, there is a challenge to exactly transfer the target composition into the deposited thin film. In addition, the elemental analysis of complex composition thin films is a difficult task, since there are no standards available. We used pulsed laser deposition, a technique that has the ability to grow very complex compounds to obtain thin films of AlFeCoNiMn. ArF or KrF lasers ablated the metallic target under an Ar atmosphere. The films were collected on Si substrates at room temperature to maintain the amorphous or nanocrystalline structure of the target. After deposition, the films structure and mass density was investigated by grazing incidence X-ray diffraction and X-ray reflectivity, while the elemental chemical composition was investigated using Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy and energy and wavelength dispersive X-ray spectroscopy. A comparison of the elemental composition results was performed, which highlighted the advantages and limitations of the PLD technique and helped the optimization of the deposited films composition.

Resume : Previously we reported on the synthesis of W nanoparticles (WNPs) using a cluster source based on magnetron sputtering combined with gas aggregation (MSGA). The magnetron sputtering process is sustained by a 13.56 MHz radio frequency discharge in pure Ar. In these works, we observed the ceasing of the deposition rate to zero in a defined interval of time (up to 30 minutes for a new sputtering target). This experimental observation suggests that the nucleation of the WNPs may be sustained by one of the residual gases from the aggregation chamber. In the case of WNPs we identified hydrogen (H2) to be one of the gases sustaining the synthesis of the WNPs in a MSGA system. This result was observed during the search for incorporation of hydrogen in WNPs during their synthesis. Indeed, by mixing a small amount of H2 to Ar, a sudden increase of the WNPs production rate was observed. The addition of hydrogen triggers also an oscillatory behaviour of the deposition rate and of the discharge parameters (cathode self-bias voltage, pressure and intensity of the plasma optical emission lines), while the average deposition rate remains constant in time. Beside the process influence, the WNPs morphology was also noticed. Acknowledgements: This work has been financed by the Romanian Ministry of Research and Innovation in the frame of Nucleus programme INFLPR 4N/2016, MALASENT

Resume : Diamond-like carbon (DLC) films have superior properties that can be tailored to meet the specific requirements of electronic applications. DLC films have very strong tolerance for X-ray irradiation, IR transparency, and chemical inertness. Besides, their mechanical properties such as high hardness and low friction coefficient are now used in numerous industrial applications, including razor blades, magnetic hard discs, critical engine parts, mechanical face seals, scratch-resistant glasses, invasive and implantable medical devices and microelectromechanical systems. The main goal of our investigation is to highlight our achievement in the synthesis, characterization and application of DLC films for II-VI-based radiation detector improvement. We shall present the elaboration of ion-plasma technique for efficient surface processing of CdZnTe and HgCdTe/CdZnTe structures to provide modification of the surface state and passivation of the crystal surface, in particular by DLC films. Optical and electrical properties will investigate. We shall discuss properties of CdZnTe-based X/gamma detector and HgCdTe/CdZnTe-based IR detector with DLC coating.

Resume : Eu-activated Y2O2S is an important red-emitting phosphor due to its high luminance efficiency, good stability as well as non-toxicity. Although Y2O2S:Eu can be prepared by various deposition methods, most of them require high process temperatures in order to obtain a crystalline structure. In this contribution, we report on the structural and spectroscopic properties of Eu-doped Y2O2S prepared by atomic layer deposition (ALD) at 300 °C. To grow the Y2O2S thin film, (CH3Cp)3Y, H2O and H2S were used as yttrium, oxygen, and sulphur precursors, respectively, whereas Eu(thd)3 was used as the Eu dopant precursor. The composition of thin film layers and doping configuration could be changed by modifying the pulsing sequences. Eu was introduced into the Y2O2S matrix in combination with either H2S or O3. FTIR, XPS, XRD and PL measurements were carried out on the obtained thin films. XRD measurements showed a crystalline structure of the films when the Eu precursor pulse was followed by a H2S pulse whereas XPS analyses showed that SO42- was formed when the Eu precursor pulse was followed by an O3 pulse.. Photoluminescence measurements showed that the oxidation state of Eu can be regulated through the doping configuration: emission above 550 nm was dominant when the Eu/O3 pulse sequence was used while the Eu/H2S pulse sequence led to a dominant emission below 500 nm. Correlations between growth parameters, thin films composition and luminescent properties are discussed.

Resume : Pulsed-injection metalorganic chemical vapor deposition (PI-MOCVD) method was used for the deposition of thin nanostructured La1-xSrx(Mn1-yCoy)zO3 (LSMCO) films due to colossal magnetoresistance phenomena, enabling application of these manganites in magnetic field sensing. The composition of the films and exact doping level of Co was determined by inductively coupled plasma mass spectrometry (ICP-MS). The novelty of the research is not only the certain doping level of Co, but also the nonstoichiometry of Mn leading to the change of structural, transport and magnetic properties of the nanostructured LSMCO films. It was determined that Mn nonstoichiometry influences the transition temperature. Additionally, it was observed that for epitaxial films (LSMCO grown on LaAlO3) the transition temperature is very close to Curie temperature, whereas for nanostructured films (LSMCO on ceramic substrate), those transition temperatures differ. The transition temperature is also influenced by the Co content in the manganite structure, leading to the decreased temperatures with the increased of Co content. The increase of Co improves the magnetoresistive properties of the LSMCO films: increase of magnetoresistance with Co content up to magnetic fields of 21 T. The grown nanostructured LSMCO films were used for the fabrication of of B-scalar magnetic field sensors (measure magnetic field independent of its direction) operating in a wide temperature and magnetic field range.

Resume : Aluminum nanocomposites containing 2%, 5% and 10% TiCN nanoparticles were produced as rods with 12 mm diameter by means of preliminary cold volume compression and succeeding hot pressing. Thin lamellas were cut from the rods and were alloyed by electron beam method in a suitable mode on the aluminum substrate. The electron-beam treatment (EBT) process was carried out using Leybold Heraus (EWS 300/15–60) electron beam equipment. The technological parameters, namely accelerating voltage (U) = 60 kV, beam current (Ib) = 15-30 mA, speed of the specimen motion (V)=0.5-5 cm/sec, scanning frequency (f) – up to 10 kHz. The technological conditions of the electron-beam process were systematically varied. Composite coatings with metallurgical bond with the substrate were obtained. Light microscopy (LM), Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used for characterizing the microstructure. The phase composition of the obtained specimens was studied by means of X-ray diffraction (XRD) using CuKα characteristic radiation (λ=1.54 Å). The tribological properties were discussed with respect to the applied technological conditions of the EBT and corresponding microstructure and crystallographic structure of the formed layers. Nanocomposite coatings with improved hardness and wear resistance were obtained which is necessary as exploitation surface properties of automobile and aircraft parts.

Resume : Multi-layers compose of the overlaps of two different kinds to materials with characteristic length, thickness of each single layer can be controlled within a few nanometer or smaller order of magnitude. Because of the promising nature in the field of physics and materials such as the giant magnetism resistance effects?electron screening effects, super-hard effects?multi-layers attract a large number of scientists concerning about application prospects in the optics, electronics, information techniques and other functions materials. In this paper, the low-stress Fe/Au multi-layers are prepared by magnetron sputtering deposition with the multi-targets. The correlations between residual stress and Ar pressure, sputtering power and the number of periods of multi-layers [Fe5nm/Au5nm] have been studied. The experimental results reveal that the residual stress in Fe/Au multi-layers is tensile stress and increases with Au sputtering power while maintaining the Fe sputtering power; On the other hand, the stress decreases with the growing of the cycle and when the cycle is more than 200, the residual stress can be treated as zero. The calculated root-mean-square of roughness of the Fe/Au multi-layers on the SiN substrate is about 7.65nm, and has an impact on the residual stress in the multi-layers.

Resume : Fully ‘Erase-free’ multi-bit operation (3-bit in this research, 7-low resistance state (LRS) and 1-high resistance state (HRS)) is demonstrated in the W/HfO2/TiN stacked resistive switching device. The term ‘Erase-free’ means that a desired arbitrary digital state in multi-bit operation can be achieved without initializing of the resistance state of device. Because of the ‘direct’ movement between different resistance states, the ‘Erase-free’ based multi-bit operation can save the operational energy compared to the ‘Non Erase-free’ case. The most important characteristic to realize the ‘Erase-free’ based multi-bit operation is a gradual resistance change with applied electric pulse stimuli in both writing and erasing processes. In addition, some prerequisites, such as electrical-circuit-controlling algorithm and high reliability of resistive switching device itself, are required. Experimentally, up to 75% of operational energy saving and near the state-overlap probability of 6σ are confirmed simultaneously in ‘Erase-free’ operation compared to the ‘Non Erase-free’ case. These results of this research can be a positive step to realize the next-generation non-volatile memory applications. The detailed experimental processes, electrical measurement results, and microscopic chemical analyses will be included in presentation material.

Resume : Chalcogenide glasses are attractive optical materials due to their high transmittance, high refractive index, high optical nonlinearity, and low optical losses. Many applications of these glasses require their surface patterning with micro-/ nano- strictures, such as diffraction gratings, antireflection morphologies, or waveguides. Up to date, such patterning was possible by laser writing, which provides, however, low throughput and limited resolution. Alternatively, the surface of chalcogenide glasses can be nanoimprinted, since their glass transition temperature ranges between 100 oC to 300 oC, depending on their composition. However, the high temperature and pressure applied during the imprint would also deform the shape of the substrate itself, and damage its optical functionality. Thus, optical components made of chalcogenide glass cannot be directly patterned by standard nanoimprint. Here, we demonstrate two novel approaches for the direct surface nanoimprint of As2Se3 - a chalcogenide glass with the glass transition temperature of 165 oC. Full pattern transfer into the glass surface is observed, without deforming the substrate. The first approach is based on a nanocomposite mold made of carbon nanotube matrix and Polydimethylsiloxane PDMS resin. The set up is controllably assembled and radiated by an infrared bulb. By this method, only As2Se3 surface that contacts the mold is heated above its glass transition temperature and nanoimprinted without deforming. In addition, by this approach we can also imprint chalcogenide lens with full pattern transfer. In the second approach, As2Se3 solution is applied onto As2Se3 substrate by spin coating and baked. In this case, a standard nanoimprint with PDMS mold was done by applying conductive heating and mechanical pressure, to yield the full pattern transfer with no damage to the substrate shape, similarly as in the first approach. To demonstrate the applicability of our novel approaches for optics, we imprinted diffraction gratings onto the As2Se3 surface, and characterized it in the reflection mode (for visible wavelength, and in the transmission mode (for near infrared wavelength). In overall, our work presents two novel, unconditional approaches for the direct micro-/ nano-structures of chalcogenide glasses and paves the way to their numerous applications in the future optical components.

Resume : Bilayers of ferromagnetic/non-magnetic metallic films are used to investigate spin-to-charge current conversion in modern magnetism. We report on the determination of the crystal symmetry breaking at the Fe/Pt interfaces and its effects on the magnetic properties, where Pt thickness deposited on a constant Fe layer, found to be crucial for the static magnetic properties. The coercive field raise, caused by changes on the magnetic anisotropy in thinner (< 8nm of Pt) systems as magneto-optical Kerr effect and SQUID measurements provided, led as to relate the interface morphology and roughness with magnetism and to determine the interface-induced phenomena for the Fe/Pt epitaxial, single-crystal bilayers. Simulation of the epitaxial model confirmed by the structural study via X-ray diffraction, X-ray photoelectron spectroscopy and High-resolution electron microscopy. The increased roughness provided from an atomic scale diffusion near the interface, during the deposition and annealing process, enhance spin-driven phenomena. This research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project ?Strengthening Human Resources Research Potential via Doctorate Research? (MIS-5000432), implemented by the State Scholarships Foundation (???), and has been supported by EU in the framework of the NetFISiC project (Grand No. PITN-GA-2010-264613).

Resume : Lately, the demand for architectural integration of solar thermal collectors led to the need of using adapted coloured façades, without affecting the overall performance of the collectors. An optimal solution can be achieved by using optical interference filters comprising abundant materials. In this work we report on the deposition of SiO2/TiO2 multilayers on Si and glass substrates by reactive magnetron sputtering of stoichiometric oxide targets. A colored optical interference filter was designed by optical modelling, targeting for a multilayer structure with superior optical transmittance, combined with a green-yellow reflected color. Surface profilometry, X-ray reflectivity, SEM, spectrophotometry and AFM were used to investigate the thickness, optical properties and surface roughness of the investigated samples. The optical characterization of the multilayer revealed a reflectivity peak (~ 54 %) at about 574 nm (corresponding to a green-yellow color), a visible reflectance of ~ 45.3 % and a solar transmission of about 80 %, along with a good thermal stability in air up to 200 C. The mechanical testing by nanoindentation and nanoscratch indicated a hardness of 7.18 GPa, a reduced Young modulus of 88.31 GPa, good scratch resistance up to 13 mN, and a hardness to modulus ratio of 0.081, indicative for good wear resistance. We acknowledge the support of the Romanian Research & Innovation Ministry: 2019 Core Projects and Project PROINSTITUTIO - contract no.19PFE/17.10.2018.

Resume : Multicomponent refractory metal nitrides have drawn great attention as advanced coating materials in the past decade. Their applications include diffusion barrier layers[1], hard wear-resistant coatings[2], and corrosion-resistant coatings[3]. In this work, a series of Ti-Nb-Zr-Ta nitride coatings were deposited using reactive magnetron sputtering with four segmented targets, aiming for applications as corrosion-resistant layers in fuel cells and batteries. The morphology and microstructure of the coatings were optimized to avoid formation of voids by changing reactive nitrogen flow, and deposition temperature. Coatings were characterized by electron microscopy, compositional analysis, and X-ray diffraction. Coatings deposited with nitrogen flow ratio [RN=N2/(Ar N2)] increasing from 1.5% to 30.1%, were all observed to show single solid solution FCC phases. For coatings deposited with a nitrogen flow ratio of 1.5%, a (002) preferred orientation of FCC was observed in coating deposited at 400 ºC. The structure in coatings deposited above 500 ºC was BCC rather than FCC. Effect of nitrogen content in the film and morphology on the electrical, mechanical and corrosion properties were studied with four-point probe, nanoindentation and scanning droplet cell microscopy, respectively. For example, the resistivity of TiNbZrTaN solid solution films were strongly affected by nitrogen content ranging from 197.7 to 424.1 μΩ cm. [1] M. H. Tsai, C. W. Wang, C. H. Lai, J. W. Yeh, J. Y. Gan, Applied Physics Letters 92 (2008) 052109. [2] K. S. Chang, K. T. Chen, C. Y. Hsu, P. D. Hong, Applied Surface Science 440 (2018) 1–7. [3] C.H. Lin, J.G. Duh, Surface and Coatings Technology 203 (2008) 558–561.

Resume : Magnetron sputtering combined with in situ and real time diagnostics can provide some valuable insights on the thin film growth dynamics, enabling a deeper understanding of the film formation processes and their interplay with stress evolution. The control of the film microstructural attributes can be achieved by strategies based on interfacial or alloying design. However, mechanisms responsible for this tailoring are not yet fully understood. Here, we report a study on high-mobility metals growth on a-Ge buffer layer and compare the results with co-deposition of Cu-Ge [1]. In situ monitoring -based on curvature (MOSS), resistivity, and optical reflectivity (SDRS) measurements- was used to study the growth mode and subsequent microstructure changes of Ag and Cu thin films sputter-deposited on amorphous germanium (a-Ge) layer and on SiOx. Ex situ characterization (STEM, XRD) allows an in-depth understanding of the correlation between early stages of growth and microstructural properties for both systems. For both metals, a-Ge acts as a wetting layer, thereby affecting nucleation and coalescence stages, as well as subsequent grain structure and stress development. A stronger chemical affinity with Ge is revealed for Cu films compared to Ag, leading to interfacial germanide formation. The SDRS data were analyzed and modelled using calculations of the optical reflectivity taking into account different layer stacking and crystal imperfections. 1. C. Furgeaud et al. Acta Mat. 159 (2018) 286-295

Resume : The aim of this work is the study of Mn/V doped nanostructured ZnO films prepared by combining the physical and chemical methods to obtain a performant piezoelectric material, used in MEMS systems for harvester applications. Hydrothermal technique (HT) is the most appropriate method to obtain such nanostructured films (as nanowires, nanorods, nanotubes). It offers a very easy control of the particle shape and size of the films, easiness to embed the dopants, combined with a low process temperature. To improve the adherence and the crystallinity of the hydrothermal layers, an initial seed layer was deposited by a physical method, namely Atomic Layer Deposition (ALD). Thus a very smooth layer with good crystallinity was obtained which further enhanced the adherence of the next ZnO-HT layer.) The final ZnO-HT films deposited on ZnO-ALD seed layers contain a structure formed by nanorods with hexagonal cross section of 50 nm and length which varies from 30 to 300 nm. EDX and XRF showed the existence of Mn in all samples, even in those with 1% Mn. The dopant concentration influences the sample morphology (as seen by SEM) and leads to the decrease of the grain size of the upper layer. The results obtained on ZnO films were compared with those obtained on PZT films. Acknowledgements: The financial support of the projects: STAR-ROSA 164/2017 and EU (ERDF) and Romanian Government under POS-CCE O 2.2.1 project INFRANANOCHEM - Nr. 19/01.03.2009 are gratefully acknowledged.

Resume : Hydrogen has been considered as the green energy carrier to substitute gradually depleted fossil fuels due to its virtues holding high energy density and zero environmental discharge. Electrocatalytic water splitting is one of the most effective approach to generate hydrogen fuel, which involves two half reactions, namely hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The design of efficient and low-cost electrocatalysts to reduce the large energy barriers of water splitting is challenging. Transition metal selenides have served as potential alternatives to noble metal due to high electroconductivity, while their electrocatalytic performance is still far from being satisfactory. In this work, we report the construction of intrinsically metallic NiCoSe2 films on carbon cloth with crimped nanosheets configuration and highly open structure. The unique morphology endows NiCoSe2 with the superhydrophilic property, leading to the close affinity with electrolyte. Density functional theory (DFT) calculations indicate the combined contribution of Ni and Co elements to the electronic structure of bimetallic selenides, revealing the strong interaction of bimetals toward enhanced electrical conductivity. Benefiting from the cooperative effects of the structure features, metallic nature and bimetals effect, NiCoSe2 exhibits superior electrocatalytic performance and robust durability toward overall water splitting with the low overpotentials of 112.7 mV for HER 255.8 mV for OER to deliver 10 mA cm-2 current densities, indicating an enticing prospect in water electrolysis.

Resume : High temperature thermal treatment is a fundamental method to enhance the crystallinity of materials or to recover its intrinsic properties after processes. However, the thermal treatments has become an inaccessible technic since the treatment temperature is usually limited by such as transparent or flexible substrate. Here, it is introduced the microwave ‘induction’ heating as a selective and fast heating method for conductive thin film. In different with the conventional microwave dielectric heating for electrically polarized molecules, the microwave induction heating has mechanism that strong current induced by oscillating magnetic field in giga-hertz frequency generates ohmic heat in conduction thin film. A 20nm-thick silver thin film sputtered on 5mm-thick glass substrate for low thermal emissivity coating has been selectively heated more than 550oC in 200ms without thermal damage by the microwave induction heating, while the temperature of glass substrate is maintained around room temperature. The surface resistance of the silver thin film is reduced to near 30% due to crystallinity enhancement, in results, reflectance in IR region and transmittance in VIS region are increased.

Resume : Ga2O3 is a wide band-gap semiconductor (with Eg= 4,7eV), very promising due to its gas sensing properties as well as its possible applications as UV transparent conductive oxide. Its refractive index is close to the square root of those of most III-V semiconductors, therefore it can be used as an antireflective coating. Its photocatalitic properties make it very favourable, as its conduction band is located at -7.75eV compared to the vacuum level, therefore it is a much more versatile material for water splitting and hydrogen generation than most oxides, especially in its nanostructured forms. In the present work, nanostructured Ga2O3 was prepared using hydrothermal growth. A water based solution of GaCl3 and urea was used for the deposition of the different structures between 80°C and 180°C deposition temperatures. It was determined, that the different deposition conditions could result in the growth of continuous films, or high aspect ratio nanostructures. Si, sapphire and different Ga2O3 films were used as substrates, and their effects on the growth was also determined. As the grown nanostructures were amorphous, different heat treatments were used to induce crystallisation, and thus β-Ga2O3 phase could be achieved. The morphology of the layers was characterised with electron microscopy, their structure was examined by X-ray diffraction and transmission electron microscopy. Their optical properties were characterised by ellipsometry.

Resume : To apply the strain sensor to wearable and stretchable electronics, we fabricated cost-effective and stretchable Ag nanoparticle (NP) electrodes on polyurethane (PU) by using simple screen printing at atmospheric ambient. By wave and horseshoe-type patterning as a function of line-width, we simply fabricated the stretchable Ag NP electrodes with sheet resistance of 1.64~2.85 Ohm-square. Using a lab-made stretching test system, resistance change of both wave and horseshoe type Ag NP electrodes was measured and compared with increasing strain to determine the usage window of the Ag NP electrodes as stretchable electrodes. The Ag NP electrodes with 3 mm line width showed strain of 20% (wave pattern) and 15% (horseshoe pattern) which are apt for stretchable strain sensors and stretchable interconnectors. In addition, outer and inner bending test results showed that the screen-printed Ag NP electrodes have good flexibility. A possible stretching mechanism was suggested to understand the good flexibility and stretchability of screen-printed Ag NP electrodes on PU substrate. Furthermore, we applied a screen printed Ag NP electrodes as stretchable interconnects for light emitting diodes (LED) and strain sensors. Effective detection of motion by Ag NP electrodes based strain sensor indicates the potential of Ag NP electrodes as a stretchable electrode for wearable and stretchable sensors.

Resume : Nowadays, plastics which are not landfilled or recycled are found in nature polluting the seas and the oceans. In this way, plastic marine debris has become one of the biggest world problems. To overcome this environment issue, biodegradable polymers have been studied thus far. However, most polyester-based materials with good biodegradability in soil do not degrade or degrade very slowly in oceans such is the case of PBAT. In order to improve the degradability of PBAT materials, we proposed the use of ultraviolet (UV) irradiation to modify the polymer surface and tune the wettability. Here we present a degradation study of PBAT films under aqueous environment varying the salinity and pH of the medium. Indeed, the effect of UV radiation in the presence of oxygen with different exposure times was also studied as well as the fabrication technique used to prepare the films (casting, electrospinning and 3D printing). The hydrophilicity increases with the irradiation time of the surfaces due to the increase of polar groups (C=O and C-OH) grafted on the polymer surface as observed by XPS and FTIR. Degradation tests were done in deionized water, seawater and PBS buffer solutions (pH 4, 7 and 10). Due to its higher porosity and lower thickness, electrospun films showed a faster degradation with 20% of mass loss in only 6 weeks compared to 2% and 1% of casting and 3D printing films, respectively. Indeed, the irradiation time accelerate the degradation of PBAT electrospun films mainly in marine environment. This work shows that UV irradiation could be successfully used to accelerate the degradation rate of PBAT films for the use in aqueous environment.

Resume : The reactive sputtering of Cu in Ar/O2 atmosphere was employed using an active feedback loop to control the deposition process and the corresponding properties of the CuOx films. The loop uses the plasma emission intensity as an input parameter for the control of O2 flow, so that the ratio of selected Cu and O emission lines is kept constant during the deposition. The PID controlled feedback loop enables a stable functioning over long durations, with corrections done in few seconds after system perturbation. The well-known hysteresis effect specific to reactive magnetron sputtering is therefore avoided, allowing to obtain a stable process inside the hysteresis loop, in otherwise unattainable conditions. The structural transition from Cu rich films to CuO was assessed by XRD analysis. However, the elemental composition determined by RBS indicated an excess of Oxygen, as compared to the expected Cu/O ratio. Corroborating these results with the Tauc optical band gap values determined from the absorption spectra (1.16 to 2.59 eV), the Cu2O - Cu4O3 – CuO transition was identified, corresponding to the decrease of the Cu/O lines intensity ratio.A direct relation between this control parameter and process conditions was established, enabling the tuning of the film properties in a wide range, adaptable for various applications. We acknowledge the support of the Romanian Research & Innovation Ministry: Core Project-2019 and PROINSTITUTIO Project – contract no. 19PFE/17.10.2018.

Resume : Solid oxide fuel cells (SOFCs) are next generation energy conversion devices due to advantages such as high efficiency, eco-friendliness, and fuel flexibility. Conventional SOFCs, however, are usually operated at high temperature regime above 800 ℃ and have limitations in applying to various fields, e.g., portable applications. Therefore, low temperature SOFCs (LT-SOFCs), which can be operated at temperature under 500℃, are being widely researched. At low temperature, however, the activation process is slowed at the interface between the electrolyte and the electrode, especially at cathode interface due to the high activation energy (~1eV) of the oxygen reduction reaction (ORR). Therefore, the adoption of materials to facilitate the cathode activation process is crucial to improving LT-SOFC performance. In this regard, CeO2-based materials may promote ORR due to its high surface exchange coefficient as well as high oxygen-ion conductivity. In this research, an ultra-thin atomic layer deposited (ALD) ZrO2-doped CeO2 (ZDC) film (~ 20 nm) with various doping levels (doped at 0, 20 and 60 mol%) is fabricated, applied to the cathode interlayer of LT-SOFC, and electrochemically characterized. We show that the thermal stability of ALD ZDC thin films can be improved, e.g., grain coarsening is impeded, compared to that of pure CeO2 thin films, which demonstrates that doping helps to preserve the catalytically-active surface grain boundaries of thin films. Finally, the activation resistance of the SOFC with optimally-doped (i.e., 20 mol% doped) ALD ZDC cathodic interlayer is reduced by 70 % compared to the cell without the interlayer, and therefore, the maximum power density is improved by 57 %.

Resume : Dealloying is a broad method to fabricate nanoporous gold (NPG) by etching gold/silver alloy in nitric acid. Here we reported the fabrication of controllable ultrafine NPG film with pore sizes about 5 nm by a simple modified dealloying method. The mechanism of this new synthesis method was also discussed. SEM and TEM results show the surface structures of the as prepared NPG film. The NPG film with ultrafine pore sizes exhibit improved surface enhanced Raman scattering (SERS) sensitivity. While we focused here on alloy films, this convenient, low-cost and scalable method in this study are generally applicable to other metallic structures like metal wires for improving their performance in many applications.

Resume : Dental frameworks made of ceramic veneered NiCr alloy are widely used in dentistry due to their superior mechanical properties and favourable aesthetic outcomes. In this study, MeSiON layers (Me: Cr or Zr) were used, aiming to increase the bond strength of the outer ceramic layer to the NiCr dentures. The interlayers were deposited using the cathodic arc evaporation technique and the substrate bias voltage was varied from -50 to -200 V, with 50V steps. The characterization of the MeON coatings revealed the dependence of the elemental and phase composition, surface roughness, wettability and substrate adhesion, on the substrate bias values. The influence of the different MeON coatings used as interlayers between the NiCr substrate and the ceramic outer layer on the bond strength of the system was analysed and correlated with the surface roughness and surface wettability. The mechanical investigation of the NiCr-MeON-ceramic system revealed a superior value of the fracture force applied to the system in the case of ZrON coatings deposited at a bias voltage of -200V. Considering the superior biocompatibility of Zr compared to Cr, ZrON coatings prepared at the highest substrate bias voltage may represent a valuable biomaterial for the lifespan increase of the NiCr based dentistry. We acknowledge the support of the Romanian Research & Innovation Ministry: Core Project-2019 and PROINSTITUTIO Project - no.19PFE/17.10.2018 and MedicalMetMat Project no. 60PCCDI/2018.

Resume : The DLC coatings is of great interest in many industrial applications. Their many advantages, such as high hardness, low friction coefficient, chemical inertness etc, comes with the challenge regarding their adhesion on the substrate, due to usually high levels of compressive stress. In this contribution we report on the deposition of hard DLC coatings on industrial scale unit, both on planar metal samples and diesel injector pins. The adhesion to the substrate is ensured by using a Ti based multilayer structure, for total film thicknesses up to 1.5 microns. The hard coatings are obtained via a HIPIMS based process on C target, both in pure Ar and Ar/C2H2 gas mixtures. Synchronized pulsed biasing was used to optimize the flux of ions to the substrates, the compressive stress levels being kept bellow 2.5 GPa, for film hardness going as high as 30 GPa. Tribological investigations on flat samples revealed low friction coefficients of 0.1 and good wear behavior. The stability of the coatings was tested by standard industrial testing, according to MIL, ASTM, “OCLI – spec. 6040011”. The most frequent failure observed occurs between the hard coating and the interlayer. Best process conditions were identified, achieving coating stability for: Adherence, Abrasion, Friction, Chemical Resistance, Salt Fog, Humidity, Temperature, Thermal Shock. This work was supported by M-ERA.NET project TANDEM through the Romanian Ministry of Research and Innovation, UEFISCDI, project No. 56/57 2016.

Resume : Multicomponent alloy thin films, a relatively new area of study in materials science, have numerous applications. Amongst these materials are variants of the Cantor alloy (CoCrFeMnNi) which display a relatively simple crystal structure and thermodynamic stability regardless of their complex chemical composition thereby, finding use as hard wear resistant, corrosion and oxidation resistant coatings [1], [2]. The present study deals with developing corrosion resistant multicomponent thin films for application in batteries and bipolar plates of fuel cells. CrFeCoCu films were grown on silicon substrates by a combination of DC and RF magnetron sputtering with segmented targets. The dependence of composition and structure of the metallic and nitride films on process parameters such as temperature (room temperature-500°C) and N2 flow ratio (0-9%) were studied. The structure, morphology and composition were characterized by electron microscopy, chemical analysis, and X-ray diffraction. Films with atomic composition Cu3.1FeCo2.7Cu5.6 had a growth morphology which consisted of domed columnar clusters of ranging height (700 nm-1 µm) separated by gaps through the film. This morphology might be due to the mixed FCC and BCC phases. Inserting nitrogen into the film reduced the roughness and increased the density. Electrochemical, mechanical, and optical characterization was carried out on the nitride coatings. They were found to be suitable candidates for application as corrosion resistant coatings. [1] B. Cantor, I. T. H. Chang, P. Knight, and A. J. B. Vincent, “Microstructural development in equiatomic multicomponent alloys,” Mater. Sci. Eng. A, vol. 375–377, no. 1–2 SPEC. ISS., pp. 213–218, 2004. [2] Shaginyan, L. R., et al. "The Properties of Cr–Co–Cu–Fe–Ni Alloy Films Deposited by Magnetron Sputtering." Powder Metallurgy and Metal Ceramics 57.5-6 (2018): 293-300.

Resume : Based on their high temperature strength, outstanding creep resistance as well as excellent oxidation resistance, Si and B alloyed refractory metals such as the Mo Si B system are promising candidates for next generation turbine materials. Here, the poor oxidation resistance of Mo¬ – dominated by the formation of volatile MoOx (so called pesting) – is impeded by the generation of a dense, glassy like borosilicate-based layer. However, providing a proper B/Si ratio is crucial for enhancing the oxidation resistance. The phase combination of bcc-Mo, c-Mo3Si, and T2-Mo5SiB2, as occurring in the three phase field known as Berczik Triangle, provides the ideal ratio of boron and silicon to form a highly stable borosilicate-based scale. To access these interesting properties for further bulk materials, PVD is a proper technique to deposit Mo Si B thin films. However, during PVD deposition, the kinetic input during film growth limits the formation of crystalline phases within the Berczik triangle, especially at typical deposition temperatures. Alloying titanium is known to stabilise in particular the T2-Mo5SiB2 phase for bulk alloys. In this study, we present a detailed analysis of the Mo (Ti) Si B system deposited by magnetron sputtering, varying the Ti content as well as the deposition parameters in a wide range. The obtained coatings were characterised in the as deposited state and upon annealing, using thermal analysis, XRD, as well as high resolution techniques such as TEM and APT.

Resume : Titanium nitride thin films were fabricated by glancing angle deposition with DC magnetron sputtering. The effects of substrate temperature (300 ? 723 K) and substrate inclination angle ( 5° to 85°with respect to target normal) were studied at a fixed working pressure of 0.3 Pa. Scanning electron microscopy, wavelength dispersive X-ray spectroscopy and X-ray diffraction were used to investigate the morphology,the elemental composition and crystal structure of the films. Electrical properties were also studied by standard four-point probe technique. The films present diffraction lines corresponding to the cubic (Na-Cl type) structure of TiN with (111) preferred orientation. They exhibit a columnar growth, with the column tilt angle being governed by the angular distribution of the incident particle flux [1]. A biaxial texture is revealed from pole figure measurements. The N/Ti ratio was found close to ~1, indicating the growth of stoichiometric TiN films. The surface topography is considerably influenced by the tilt angle of the substrate and the substrate temperature. The electrical resistivity increases with increasing inclination angle, which is related to increasing porosity and post-deposition oxygen uptake of themore films with the more inclined columnar morphology. However, lower electrical resistivity values were found for the high temperature series, ascribed to the densification of the films and lower oxygen contamination.

Resume : Silicon dioxide films are widely applied for their dielectric, mechanic properties and also for their resistance against reactive chemicals. Thus, SiO2 protective coatings are used in microelectronics, optics or pharmaceutical industry. However, the production of high-quality films suffers from difficulties related to their chemical composition, morphological homogeneity and limitation of deposition rates. Vacuum based processes overcome these challenges, but the production is expensive and time consuming. Atmospheric pressure processes demonstrated higher deposition rates, but the chemical purity and crosslinking of resulting coatings remains critical because of carbon content and interstitial water in the polymer network [1]. We present a plasma enhanced chemical vapor deposition by means of a capacitively coupled radiofrequency plasma jet operated with argon and OMCTS. A novel design of electrodes allows generating spatially homogeneous and stable plasma with a caliber of 9 mm. The geometry integrates a nozzle for injection of precursor in the plasma. Operation properties of the source result from the last progress on self-organization published recently [2]. The films have been deposited on lead alloys, analyzed by XPS and ellipsometry. Their anticorrosive properties have been positively tested in acidic vapors of acetic acid. [1] J. Schäfer et al., Thin Solid Films 630 (2017) 71 [2] J. Schäfer et al., Plasma Phys. Control. Fusion 60 (2018) 014038

Resume : Titanium dioxide (TiO2) is attracting attention among the numerous dielectric materials, and the plasma enhanced atomic layer deposition (PE-ALD) is regarded as a very promising technology of which the self-limiting growth allows precise thickness control. In ALD technique, ALD widow is important criteria determining process conditions. Generally, it is known that growth per cycle (GPC) increases at lower temperatures than ALD temperature window since the process loses self-limiting mode by condensation. However, we detected GPC increase in self-limiting mode when the PE-ALD TiO2 thin films using tetrakis(dimethylamido)titanium (TDMAT) were deposited with short plasma time at the temperatures lower than the decomposition temperature of the precursor. TiO2 films were deposited on silicon by PE-ALD using TDMAT and O2 plasma to investigate the change in film properties derived from different plasma time at between 100 to 200 ℃. As a result, GPC increased by a factor of 1.8 with short O2 plasma time at 100 ℃, and the refractive index (RI) varied from 4.1 to 4.4. Wet etch rate performed with SC1 was 12 times faster compared to the films prepared with longer plasma pulse, and it is in agreement with the composition difference derived by X-ray photoelectron spectroscopy. In this talk, we will present the effect of process temperature and O2 plasma time on the PE-ALD grown TiO2 film properties including electrical properties and our proposal for the understanding of the phenomena.

Resume : The paper reports on antibacterial properties of Ag-doped Al2O3 nanolayers deposited by RF reactive magnetron sputtering on eyes contact lenses. The study is provoked by the need of suppressing the infections caused by pathogenic microorganisms following the placement of contact lenses, which brings about the necessity of forming coatings with antibacterial properties. The surface elemental composition and the morphological characteristics of the coatings are investigated by XPS and SEM measurements. Further, the microbiological studies are conducted to establish the antibacterial action of the Ag/Al2O3 nano-layers against Gram-positive and Gram-negative bacteria. The strongest action of the Ag/Al2O3 layers is found against Pseudomonas aeruginosa and Escherichia coli - full inactivation after 5 hours; Staphylococcus aureus–full inactivation after 12 hours. The optical transmission of the as-deposited contact lenses was measured by UV-VIS spectrometer. The performed analysis showed that the Ag covering does not lead to significant drop in the lens’ transmission intensity. Our experimental findings suggest a very promising application of such antibacterial Ag/Al2O3 nanolayers regarding the reduction of eye infections when setting contact lenses. Keywords:Ag/Al2O3nanolayers, antibacterial action, contact lenses coating, RF reactive magnetron sputtering

Resume : Copper oxide is gaining considerable attention due to favorable intrinsic properties such as environmentally friendly, low cost, and reconfigurable electronic structures. Among various copper oxides, cupric oxide (CuO) and cuprous oxide (Cu2O) are well known for many kinds of applications due to their attractive electrical properties. For example, CuO and Cu2O show the p-type characteristic when they have cubic and monoclinic crystal structures. Such characteristic can be used for various applications such as gas sensor, photodiode, anode materials in batteries, thin film transistors (TFTs), solar cells, and photo-catalysts. Generally, chemical vapor deposition (CVD) and atomic layer deposition (ALD) are required for uniform and conformal thin film growth. Moreover, CuO or CuO2 can be selectively deposited by controlling the oxidation state of the Cu(II) precursors and/or reactant gas. Herein, we synthesized novel Cu(II) complexes as potential precursors for ALD. The resulted complexes were characterized by various analysis equipments such as infrared spectroscopy (IR), elemental analyses (EA), thermogravimetric analysis (TGA), and single crystal X-ray diffraction.

Resume : Nanopatterning of nanocrystalline diamond (NCD) film is widely used to locally increase the magnitude of an applied electric field and, thus, enhance its electron field emission (EFE) properties. Here, we report on oxygen reactive ion etching (O2 RIE) based nanopatterning using arrays of micellar structures as consumable masks, enabling to produce not only high aspect ratio NCD nanotips required for field amplification, but also to modify the chemical composition and, thus, the related electronic property of the surface. Using surface sensitive techniques such as X-ray and ultraviolet photoelectron spectroscopy, scanning Kelvin probe, and conductive atomic force microscopy, we investigated the effects of chemical modifications and related changes on the electronic properties of nanopatterned NCD films on their EFE efficiency. It is found that, after nanopatterning, the field required to induce EFE drastically reduced from 24.2 V/um to 10.2 V/um yielding a high and stable EFE current. We conclude that both, the lowering of the work function by plasma-induced surface modifications as well as the enhancement of the applied field by proper shaping of the surface play important roles in the enhancement of EFE properties.

Resume : In the present work the influence of silicon concentration on the surface erosion (blistering) of ZrSiN nanocomposite films after He (energy of 30 keV and doses up to 8*10^16 cm^-2) ions irradiation and post-radiation annealing at 600° C was investigated. ZrSiN nanocomposite films were deposited onto Si (001) wafers by reactive unbalanced magnetron sputtering method at the temperature of 600°C. Silicon concentration was varied from 7.1 to 23.1 at.% by changing the DC power supply of the Si target (70-250 W). The film thickness was about 300 nm. It was found that ZrSiN films consist of ZrN grains surrounded by an amorphous SiNx matrix. ZrN grain size decreases from 6 to 3 nm and the volume fraction of the amorphous phase increases from 0.49 to 0.64 with increasing Si concentration. Helium ion irradiation (dose of 8*10^16 cm^-2) did not alter the surface of the nanocomposite films; however, surface erosion was observed after annealing. It was revealed that post-radiation annealing (600°C) of ZrN and Si3N4 monolithic films resulted in the blisters formation at the dose of 5*10^16 cm^-2. A low blisters density (2%) after post-radiation annealing at the dose of 5*10^16 cm^-2 was also observed for a nanocomposite film with Si concentration of 7.1 at.%. As the irradiation dose increased to 8*10^16 cm^-2, the surface density of blisters rose significantly (up to 35%). It was found that increasing of Si concentration in the nanocomposite films led to an increase in their radiation resistance. In ZrSiN nanocomposite film with a Si concentration of 23.1 at.% the formation of blisters after post-radiation (He, 8*10^16 cm^-2) annealing at 600°C was not detected. In this work an effect of grain size and interface density on the slowing down of blister formation processes is discussed.

Resume : Multilayers with ZrN (CrN, AlN) and SiNx elementary layer thickness varying from 2 to 10 nm were synthesized by sequential sputtering from elemental Zr (Cr, Al) and Si3N4 targets at substrate temperature of 300°C (ZrN/SiNx and AlN/SiNx systems) or 450°C (CrN/SiNx system). X-ray diffraction (XRD) analysis confirms that multilayered films consist of nanocrystalline (002)-oriented ZrN (CrN, AlN) and amorphous SiNx layers. The lattice parameter of metal nitride phase for ZrN/SiNx and CrN/SiNx films is higher than for ZrN and CrN monolithic film, respectively, and it increases when reducing the ZrN (CrN) layer thickness fraction with respect to bilayer thickness that gives rise to higher compressive stress. On the contrary, the lattice parameter of metal nitride phase in AlN/SiNx films is less than in AlN monolithic film. The oxidation resistance under air has been investigated using in situ XRD, in the temperature range from 400 to 950°C, as well as by WDS and SEM methods after air annealing procedure. Oxidation resistance of multilayered films is higher than in the case of reference monolithic films and it increases when reducing the thickness fraction of metal nitride layer as well as increasing interface density. On the whole, AlN/SiNx films are more resistant to high temperature oxidation than CrN/SiNx films and, especially, than ZrN/SiNx films. The influence of the chemical composition of layers, interface density and stresses on the oxidation processes in multilayered structures is discussed.

Resume : We present our results on the optical activity of two different generic types of hybrid chiral/magnetic nanocomposites: a binary multilayer heterostructure and a metamaterial consisting of spherical, metal-coated magnetic nanoparticles embedded in an optically active medium. We obtained the associated photonic band structures and transmission spectra, through a six-vector formulation of Maxwell equations, which provides an efficient framework for general bi-anisotropic structures. Our analytical methodology, in conjunction with a two-step generalized Maxwell-Garnett homogenization approach in the case of the metamaterial, goes beyond existing approaches that involve cumbersome nonlinear eigenvalue problems. The results of our calculations, analyzed and discussed in the light of group theory, show that the proposed nanostructures exhibit some remarkable frequency-tunable properties, such as enhanced nonreciprocal polarization azimuth rotation and magnetochiral dichroism, which stem from the simultaneous lack of time-reversal and space-inversion symmetries and are enhanced by collective slow-photon modes. These modes originate from strong bending of the photonic bands at the Brillouin zone boundaries in the case of the multilayer heterostructure and localized surface plasmon resonances in the case of the metamaterial. *A. Christofi acknowledges support by the Greek State Scholarships Foundation (IKY) through the program “Strengthening Post Doctoral Research” (contract no. 2016-050-0503-7197).

Resume : In this paper the influence of material composition on structure and surface properties of bioactive coatings based on Cu and Ti has been described. Nanocrystalline coatings were prepared by innovative pulsed DC magnetron sputtering process. For their preparation multi-magnetron system was used in order to manufacture films with various copper content. The main goal of this work was the analysis of antibacterial effect and cytotoxicity of Cu-Ti films in comparison with their material composition and surface state. Due to high bioactivity of copper and high stability of titanium such nanocrystalline thin films are innovative materials for application in electronics, architecture, car industry etc. Cooper is one of the most promising metal for biomedical applications, but its stability is too low taking into consideration requirements of coating industry. For this reason addition of titanium, which exhibit self-passivation effect, is a very good way to obtain stable coatings with a controlled impact on microorganisms. In our work properties of Cu-Ti thin-film coatings in relation to antimicrobial activity (for E. coli and S. aureus) as well as their impact on the viability of cells (L929 cell line) were investigated. The physicochemical properties were examined with the aid of x-ray diffraction, scanning electron microscopy and x-ray photoelectron spectroscopy methods. It was found that all prepared films were nanocrystalline and bactericidal, but their cytotoxicity was dependent from the Cu content in the film. The analysis of coatings bioactivity was related to the copper ion migration process.

Resume : Colloidal lithography is an ability to order and self-assemble micro-sized and nano-sized colloids into well-defined shapes onto a surface. This method plays a crucial role for the development of various devices in the nanotechnology. This bottom-up approach is used for production of functional materials with complex structures, leading to a variety of materials that are of interest for many applications, such as nanoelectronics, biosensing, optical and photovoltaics devices. There are several methods for colloidal particles deposition. Among them are spin coating and Langmuir Blodgett (LB). Both of them are a large-area, robust, parallel and cheap methods, which do not always yield with close-packed hexagonal particle arrays. Long range order can hardly be obtained due to various interactions between the nanoparticles (NP) inside the solution. Our goal is to investigate whether we can direct the self-assembly process of Polystyrene NP using lithography patterning, to achieve long range hexagonal order. In addition, can we assemble the NP in different packing structure and not only in the low energy preferable state? First, we produced various lithographic patterns on Silicon substrate using negative resist. We produces hexagonal and cubic pattern structures. During the lithography process we varied the posts size and the distance between them in order to understand later what has the most effective influence on the self-assembly process. Second, we deposited the Polystyrene NP using spin coating method while tuning the appropriate NP concentration. Then, we conducted a very wide analysis using surface microscopy, Transform Fourier analysis and X-Ray diffraction decoding. We found that there is a direct connection of the post size and the distance between them on the self-assembly order. Different parameters give us different crystals types, like single or poly crystal. We saw clearly that we can direct the self-assemble using lithographic pattern. These results can contribute widely to the colloidal lithography for dipper understanding and future usage.

Resume : Nowadays science has focused its efforts on the possible methods for surface modification of metals and alloys. Titanium nitride (TiN) and titanium dioxide (TiO2) films, deposited on different substrates, have many applications because of their mechanical properties, resistance to corrosion, biocompatibility. The substrates can be different kind of metals, alloys which are used for manufacturing implants, rotary dental instruments, endodontic instruments, etc. Therefore, in this study, TiN/TiO2 multilayer coatings were deposited on stainless steel 304 substrates and endodontic files by DC magnetron sputtering. The structure of the coatings was observed by XRD (X-ray diffraction) with Cu Kα characteristic radiation (1.54 Å). The measurements were conducted in Bragg-Brentano (B-B) symmetrical mode, from 20° to 80° at 2θ scale. The step has been chosen 0.1° with counting time 10 sec. per step. The biocompatibility of the coatings was studied by CCK-8 assay of osteoblastic MG63 cells, incubated for 72 hours on the samples. Each of the files was used for mechanical preparation of 5 root canals and their surface morphology was studied by scanning electron microscope afterwards. Our results showed that the obtained TiN/TiO2 multilayer coatings have good stoichiometry and don’t suppress cell growth and spreading which means that the coatings are not cytotoxic and are biocompatible. Also the pre-coated instruments have smother surface, less debris and defects than the non-coated ones.

Resume : Niobium oxide coatings deposited on Ti6Al4V substrates by electron beam deposition and annealed at 600 °C and 800 °C were evaluated for their suitability towards dental, maxillofacial or orthopaedic implant applications. A detailed physico-chemical property investigation was carried out determine their elemental and phase composition, surface morphology and roughness, mechanical properties, wettability, and corrosion resistance in simulated body fluid solution (pH=7.4) at room temperature. The biocompatibility of the bare Ti6Al4V substrate and coated surfaces was evaluated by testing the cellular adhesion and viability/proliferation of human osteosarcoma cells (MG-63) during different culture times, up to 7 days. The results show that the coatings annealed at 800 °C produce more phase pure nanocrystalline Nb2O5 surfaces with enhanced wettability, reduced porosity and enhanced corrosion resistance properties making them good candidate for implant applications. The enhanced biocompatibility, osseointegration and lower cytotoxicity shown by the 800 °C annealed Nb2O5 coatings determined from the cellular adhesion and viability studies, confirm that these coatings have the potential to be employed for implant applications. We acknowledge the support of the Romanian Research & Innovation Ministry: 2019 Core Projects and Project PROINSTITUTIO - contract no.19PFE/17.10.2018.

Resume : The diffusion saturation of iron-based alloys with interstitial elements is widely used in industry for creating durable, hard, wear and corrosion resistant coatings on metal products operating in an extreme environment. Inexhaustible and unrealized potentialities of diffusion saturation are opened when applying such treatment for materials in the non-equilibrium state. The topical question in this direction is to clarify the mass-transfer and strengthening mechanisms of strained alloys under diffusion saturation by N and C. The effect of preliminary plastic deformation with a degree of 5-70% on nanostructured diffusion layers formation, kinetics of their growth, chemical and phase composition, microhardness, wear resistance was studied in different iron-based alloys with Cr, Ti, Ni, W, Mo and other alloying elements under the saturation with nitrogen and carbon. As a result of such treatment, the diffusion layer as a combination of nanostructured surface layers of different nitrides and a zone of internal saturation is formed. Stress and strain considerably effect on the phase formation, structure, microhardness and thickness of nitrided layers. The narrow intervals of deformations of 3-8% and 20-30% in which the considerable rise of surface layer microhardness and thickness exist. The high microhardness of the diffusion layers results from the formation of nanosized nitrides. The possible mechanisms of diffusion and mass-transfer of interstitials (N and C) in deformed alloys are discussed and the possibilities of the interstitials mass-transfer with mobile dislocations in deformed alloys according to the dislocation-dynamic mechanism are especially considered.

Resume : The combination of properties and unique features of DLC coatings makes them an interesting candidate for numerous applications. The physical vapor deposition techniques play an important role, due to their versatility and wide range of achievable film properties. In this contribution, both DC-magnetron and HIPIMS are employed to obtain hard adherent DLC coatings on both Si and metal substrates, with thicknesses ranging from 0.1 to 1 micron. It is shown that the value of the negative bias voltage plays an important role in tuning the hardness of the coatings, reaching hardness values up to 30 GPa with H/E ratio exceeding 0.15, whereas the type of biasing (RF,DC or pulsed) does not affect significantly the mechanical properties. Under optimized deposition conditions the films are dense ( ~2.5g/cm3), with a compact, featureless and column free structure throughout the entire thickness. Tribological tests revealed that friction coefficient between 0.05-0.015 is achieved, with specific wear rates comprised between 0.5-1 x 10-6 mm3N-1m-1, both for DC and HIPIMS coatings. Adhesion was confirmed by scratch testing, showing specific critical load forces ranging from 20 to 40 N and ensuring stability of the coatings for demanding applications. This work was supported by M-ERA Net project TANDEM through the Romanian Ministry of Research and Innovation, UEFISCDI, project No 56,57/2016, and National CORE Project 2019.

Resume : Metal organic frameworks are known for storage and release of gases, catalysis and molecular separation due to their intrinsic nanoporosity and high internal surface area. ZIF-8 (zinc atoms linked via methyl imidazole) stands out due to additional advantageous properties, e.g., resistance to thermal changes and high chemical stability. However, classical synthesis methods are not compatible with device integration or large area deposition, calling for a viable alternative. For our studies we employed a two-step chemical vapour deposition process, that allows for the delivery of high-quality thin films of ZIF-8 with uniform and controlled thickness. First, an ultrathin ZnO seed layer is deposited via plasma-enhanced atomic layer deposition. Acting on the substrate temperature, ranging from room temperature to 200°C, the preferred crystal orientation can be switched from (100) to (002). ZIF-8 thin films are subsequently grown by subjecting the ZnO-layers to a 2-methyl imidazole vapour, following the method presented by I. Stassen, et al.*. The resulting ZIF-8 thin films were thoroughly investigated in regard to their chemical, crystalline and morphological properties to gain insight into their orientation and growth. Synchrotron radiation studies showed a (100) preferred orientation for the resulting ZIF-8 films with a powder like structure underneath and led to the proposition of a growth model. *Nat. Mat. 15, 304-310 (2015)

Resume : A conductometric Hydrogen gas sensor was assembled by combining tungsten oxide and copper oxide. The nanocrystalline thin films of tungsten trioxide (WO3) and cupric oxide (CuO) were deposited by reactive magnetron sputtering in DC and RF mode, respectively. Additionally, some samples were top coated by CuO nanoclusters deposited by magnetron-based gas aggregation cluster source. Various architectures of sensing bilayers were designed. First, CuO thin films of various thickness were deposited on the top of WO3 (backbone layer) thin films or vice-versa. Second, the WO3 films were decorated by CuO nanoclusters of the same size. The sensorial behavior of as-deposited bilayers was studied towards hydrogen gas in synthetic air. It was observed that the addition of CuO thin film or nanoclusters enhanced the sensitivity of the pure WO3 thin film. In the case of CuO thin films, the sensitivity changes with the variation in thickness of layers (upper layer and backbone layer). On the other hand, by increasing the density of nanoclusters, the sensitivity of the CuO/WO3 system rises and after a certain amount of clusters, it behaves differently. On the basis of the sensorial behavior, XRD and resistivity measurements, we propose that the sensing mechanism is based on the formation of heterojunction in between p-type CuO and n-type WO3. In the case of clusters, the nano-junctions are formed, the bilayer structures of thin films exhibit similar behavior at certain thicknesses combinations.

Resume : Metasurfaces are nanostructured, thin-film, photonic materials capable of manipulating light on the nanoscale. One emerging application of metasurfaces is to improve light management in thin-film optoelectronic devices. Fabricating metasurfaces from Ag ink could facilitate lower cost and lower energy integration into optoelectronic devices, while increasing light localization effects within the semiconductor layer. Here, we employ nanoimprint lithography to fabricate Ag metasurfaces using Ag ink and a soft mold via a direct imprint method. For comparison, a metasurface was also fabricated using thermal evaporation of silver. Structural characterisation using dark-field optical microscopy and scanning electron microscopy analysis is carried out to examine the surface structure of the metasurface. Following satisfactory fabrication, optical reflection and transmission spectroscopy are used to characterize their optical properties. To create 2D structures the process will be repeated on the original samples by rotating the mold by 90°. In addition, analytical grating theory is employed to predict and optimise light diffraction from the Ag metasurface into large, almost in-plane diffraction angles with the aim of improving in-plane light trapping in semiconductor thin films. It is hoped that improving the light trapping will lead to more energy efficient, low cost integration of nanostructured films into emerging optoelectronic devices.

Resume : High dielectric constant thin films are ubiquitous in research as they impart enhanced properties to microelectronic applications. Novel combinations for coupling high-k and ultra-wide band gap semiconductors are being investigated for niche applications, dependent on the operation environment of the microelectronic device. Typically high-k films such as alumina are deposited by atomic layer deposition (ALD), a technique heavily dependent on the surface chemistry. This work investigates the effect of boron doped diamond (BDD) semiconductor surface functionalization on its interface quality with ALD alumina, by analyzing its susceptibility to plastic deformation, and being particularly vital for electronics subjected to physically demanding environments. Alumina thin films were deposited unto as-grown (H-BDD) and oxygen plasma treated (O-BDD) polycrystalline BDD. Microindentation analysis demonstrated plastic deformation beyond the alumina-BDD interface for H-BDD whereas O-BDD experienced plastic deformation only within the alumina layer for the tested loads. XPS analysis revealed an approximate increase of 5% in O functional groups for O-BDD compared to H-BDD. Surface kinetics suggested that additional O ligands prompted TMA precursor saturation efficiency on the O-BDD surface resulting in a stable interface formed, during initial ALD cycles, by chemisorption between Al and O ligands, which accounted for its resistance to plastic deformation.

Resume : Ge1-xSnx alloy becomes for Sn concentration higher than 8%, a direct band semiconductor with remarkable optical and electrical properties, suitable for optoelectronic devices. As expected, their properties are significantly influenced by the Sn content and the crystalline quality of the films. However, the large lattice mismatch between Ge and α-Sn (14.7%), as well as the low equilibrium solubility of Sn in Ge (< 0.01 below 500 °C), hindrance the growing of high quality films. We report on comparative investigation of Ge1-xSnx films deposited by two magnetron sputtering methods, using either RF or HiPIMS sputtering of Ge target. The influence on layer properties of the DC Sn sputtering current and the growth temperature was investigated. The sputtering was performed in an Ar H2 mixture at a pressure of 0.67 Pa. The films were deposited on Si wafers with a relaxed 2 µm Ge layer. The morphology, composition and structure of films were investigated by AFM, RBS, FTIR and HR-XRD. The crystalline quality was greatly improved by the HiPIMS growth, such as there were not evidenced the presence of polycrystalline domains or Sn segregation. From the measured IR spectra, the absorption coefficients and the optical bandgap values were determined, the latter found in the 2 – 3 µm wavelength range. We acknowledge the support of UEFISCDI-contract no.58/2016, project M-ERA.NET GESNAPHOTO, and of Romanian Ministry of Research and Innovation: 2019 Core Programs of NIMP and INOE.

Resume : Thin FePd films with L10 phase are a perspective material for ultrahigh density magnetic recording applying HAMR technology. Aim of the present work is the investigation of the phase composition, structure and magnetic properties of FePd thin films with Cu underlayer after annealing in vacuum and hydrogen in the temperature range of 600 oC-700 oC. FePd/Cu films were deposited on SiO2/Si(100) substrates at room temperature by magnetron sputtering. As-deposited and annealed films were investigated by XRD, AFM, and SQUID-VSM. It is established that the L10-FePd phase in FePd(4.7 nm)/Cu(0.3 nm) bilayers was formed after long-term annealing in vacuum at 650 oC for 20 h. The film shows hard magnetic properties with coercivity values of 2.4 kOe and 2.9 kOe in out-of-plane and in-plane applied magnetic field, respectively. However, no perpendicular magnetic anisotropy (PMA) was obtained. Annealing in hydrogen accelerates the ordering process. The L10 phase is formed at 650 oC for 1 h and the film reveals PMA. Furthermore, FePd/Cu bilayers annealed in hydrogen have lower roughness then after annealing in vacuum. An increase of the Cu underlayer to 0.6 nm leads to an increase in the ordering degree, L10 phase amount, and improves the (001) texture as well. The increase of annealing duration in hydrogen to 2 h leads to a rise in the concentration of hydrogen in the films. This results in the disappearance of the hard magnetic properties, which might be due to the influence of the introduced hydrogen on the electronic structure as well as to disordering processes.

Resume : Transition metal nitrides are widely used as wear and corrosion-resistant coatings. They possess high thermal stability, high hardness, good tribological properties. Among them, some nitrides as TiN, ZrN, and HfN possess excellent optical and electrical properties. These nitrides are widely investigated as potential plasmonic material. Zirconium nitride is considered as prominent material for its exceptional thermal and chemical stability with a low electrical resistivity. ZrN coatings are mostly prepared by different physical vapor deposition methods, among them, the magnetron sputtering is the most widely used technique. However, the reactive magnetron sputtering is very sensitive to some deposition parameters, especially the composition of Ar/N2 gas mixture. Different chemical compositions such as ZrN, Zr2N, Zr3N4, and ZrN2 can be obtained via the control of the sputtering reactive gas mixture that leads to different physical properties of the resulting zirconium nitride film. In this work, we studied the effects of Ar/N2 gas mixture ratio on structural properties of the deposited film. We deposited number coatings by RF magnetron sputtering on silicon and MgO substrates. The crystallinity was analyzed by X-ray Diffraction method (XRD). Surface morphology was studied using Atomic Force Microscopy (AFM). The chemical composition of deposited ZrN thin films was studied by X-ray Photoelectron Spectroscopy (XPS). There were found zirconium nitride and zirconium oxynitride phases. Ratios of individual components ZrN and its valence band spectra were compared for different nitrogen concentrations of the sputtering reactive gas mixture. Further work function of individual phases was measured with Photoemission Electron Microscopy (PEEM).

Resume : Nanoparticles have shown promising opportunities concerning their suitability in a plethora of applications, e.g., coatings, sensor technology, and photocatalysis. Due to their high surface-to-volume ratio, the properties of nanoparticles highly relate on their surface properties and can thus be modified by means of surface functionalization to suit for specific applications. This work aims to design a modular system that aids in direct functionalization/stabilization of gas-phase made particles and their transfer into a liquid phase immediately after particle production. Nanoparticles from a spray-flame reactor are directly subjected to an AC/DC plasma discharge for inline activation and functionalization. The purpose of the combined activation and functionalization of the as-synthesized nanoparticles is to prevent particle-particle contact leading to particle aggregation due to surface condensation reactions. This is achieved by means of direct surface coating of the as-synthesized nanoparticles by using a variety of modified silanes and siloxanes. The functionalized nanoparticles will then be directly transferred to a liquid phase. Preliminary results for the design of the coating nozzle based on CFD simulations and plasma-assisted coating of TiO2 nanoparticles with SiO2 using HMDSO as gaseous coating precursor will be demonstrated. Moreover, investigations concerning the dispersibility and stability of functionalized nanoparticles in various solvents will be presented

Resume : Vertebral body replacement is still a challenge for spine surgeons. Among the complications, surgical site infections are particularly critical and difficult to treat. Poor bone regeneration and mechanical instability are further issues, also correlated with infections. Antibacterial efficacy can be tackled by Ag introduction in the hydroxyapatite (HA) coating, provisions being made for a tailored ion-release. We report on the deposition on TiAlV alloy and subsequent characterization of HA and Ag containing HA, for spine implant application. Three different Ag doped HA monolayers and a bilayer of Ag/HA were deposited by magnetron sputtering at 700 oC substrate temperature. The coatings composition, structure, morphology and hydrophilicity were determined by EDS, XRD, AFM, contact angle, and comparatively assessed. Direct contact experiments between osteoblast cells and samples were conducted to evaluate the cell adhesion, morphology, viability and proliferation. After 3 and 7 days of culture, the morphology and behavior of cellular cultures in the presence of the coated samples were analyzed by SEM. Our findings prove that HA and Ag/HA coatings can support cell growth and proliferation without any deleterious effect, while Ag doped HA coatings caused different toxicity effects to the pre-osteoblast cells and decreased their viability. We acknowledge the support of Romanian Ministry of Research and Innovation: 2019 Core Program and of the EURONANOMED - project NANOVERTEBRA.

Resume : Bismuth-based compounds have attracted significant importance in different domains as optoelectronics, gas sensors, photocatalysis, .? Due to our interest in photocatalysis, bismuth oxide, metallic bismuth/bismuth oxide and bismuth oxyfluoride films with thickness in the range of 30-95 nm had been successfully deposited by radiofrequency reactive magnetron sputtering. This was achieved by sputtering a bismuth target at room temperature under different mixtures of Argon with the reactive gases O2 or/and CF4. Hence, we tailored the stoichiometry of BixOyFz obtaining Bi2O3, non-stoichiometric oxyfluoride films and the stoichiometric BiOF. The analysis of their structures and composition implied that the films were formed of different phases. XPS revealed the contribution of different chemical environments related to metallic Bi, Bi3+ in Bi2O3 and BiOF. The bonds between bismuth and oxygen or fluorine were confirmed by IR and Raman spectroscopy. The structural properties were determined using XRD, and it was found that the non-annealed films presented crystalline metallic bismuth and BiOF phases. However, films became more amorphous when Bi2O3 is formed. The complex composition of these films was then linked to their optical properties, investigated by ellipsometry and uv-vis spectroscopy. These analyzes revealed that the materials exhibit a high band gap value in the range of 4 - 4.8 eV depending on the oxygen to fluorine ratio but also observing light absorption in the visible range for some films. Finally, metallic bismuth/bismuth oxide and oxyfluoride films, presenting different optical absorptions, modified the photocatalytic properties of the as-deposited oxide films upon degrading methyl orange under uv-vis light.

Resume : The reflector antenna used in space communication must provide a high reflectivity for the signals in the Ka band (18-30 GHz), condition fulfilled by low resistivity materials with thickness larger than the skin depth (500 nm). Aiming for adherent and conductive to coat the modelled and TiAlV fabricated antenna, we report on low C containing Cu-C coatings deposited by HiPIMS at 200 and 400 C. Coatings with different C/Cu ratios were obtained, as resulted from RBS elemental analysis. The electrical resistivity (at room and LN2 temperatures) depended on the carbon content and also on the grain-size of the coating, as derived from XRD analysis. Mechanical properties, such as hardness, reduced elastic modulus and the scratch resistance were also determined for the Cu-C coatings, and compared to the reference Cu ones. A superior coatings’ adhesion to the TiAlV substrate was obtained, according to method B - ASTM D3359. The solar absorptance and infrared thermal emittance were also determined by Vis and FTIR measurements. On the reflector antenna demonstrator was sprayed on top of the Cu-C coating a thick thermal control coating of ZnO-silicate composite, transparent for the microwaves, such as the overall system presented the required thermo-optical properties for a space communication antenna: low solar absorptance (α< 0.2) and high IR thermal emittance (ε> 0.9). Work supported by a grant of the Romanian Space Agency - STAR Program, ITAR Project no. 135/2017.

Resume : AlN has become an interesting material for microelectromechanical-based systems such as resonators for energy harvesting, cantilevers, accelerometers, surface and bulk acoustic resonators, due to its compatibility with CMOS processing and some of its remarkable properties such as high thermal conductivity and stability, high sound velocity, low dielectric permittivity. The piezoelectric, optical and electrical properties of AlN can be tuned by allowing with transition-metal nitrides such as ScN, YN, etc. Theoretical investigations suggest that YxAl1-xN has a wurtzite structure for Y concentrations up to x = 0.75, while the piezoelectric strain constant, can be increase by 700%. However, YAlN films with high Y content are experimentally difficult to synthesize due to the low YN solubility in AlN, which favors compositional phase separation and deterioration of film texture and crystalline quality as the Y concentration is increased. Strong nonequilibrium deposition processes such as sputtering, are required to obtain high Y content c-axis oriented YAlN thin films. In this work the HiPIMS is used to synthesize (0002) textured YAlN thin films on Si(100), a standard substrate in MEMS. The effect of different deposition parameters on the morphology, composition and structure of the films were investigated by AFM, AES, EDS and HR-XRD. We acknowledge the support of Romanian Ministry of Research & Innovation: Core Program/2019 and PROINSTITUTIO Project, contract no.19PFE/17.10.2018.

Resume : We studied different Cr-based multilayers aiming the improvement of the bond strength between the metallic (CoCr) and ceramic component in dentistry. The multilayers were obtained by cathodic arc evaporation on CoCr alloy, from Cr and Cr-Si (84 at.% Cr, 16 at.% Si) targets, in a N2 O2 mixture. Three types of coatings were deposited: CoCr/CrSiN/CrSiON, CoCr/CrSi/CrSiN/CrSiON and CoCr/Cr/CrSiN/CrSiON, selected because higher amounts of metals at the substrate interface might enhance the adhesion, while the presence of oxygen in the outer layer leads to the formation of oxides during the heat treatment necessary for the ceramic component, thus increasing the adhesion to the ceramic. The plain and coated CoCr samples were characterized in terms of electrochemical and mechanical properties. Viability and metabolic status for cells proliferating on the coatings surfaces was evaluated by exploring the ATP-levels using the CellTiterGlo assay. CoCr/Cr/CrSi/CrSiN/CrSiON multilayer exhibited the best corrosion performances and presented also higher cell proliferating and the best survival rate and metabolic activity in contact with human gingival fibroblasts. Due to its high number of interfaces, it had the rougher surface, such as it presented the best bond strength value of the overall coating, ceramic included. We acknowledge the support of the Romanian Research & Innovation Ministry: Core Project-2019,PROINSTITUTIO Project 19PFE/17.10.2018 and MedicalMetMat Project 60PCCDI/2018.

Resume : Heterostructured cathode has been attractive for improving the oxygen reduction reaction kinetics by loading the catalyst on the cathode [1,2]. Atomic layer deposition has a strong advantage for distributing the catalyst uniformly even on the 3-D complex structure such as solid oxide fuel cell (SOFC) cathode [1-6]. Here we fabricated amorphous lanthanum strontium cobaltite by using atomic layer deposition and treated it on La0.6Sr0.4Co0.2Fe0.8O3-δ surface to prepare heterostructured cathode for SOFC [6]. The power density of the cell using heterostructured cathode is enhanced when comparing to the bare one at 500–600 °C due to decreased polarization resistance originated from enhanced oxygen reduction kinetics. By calculating the oxygen p-band center using density functional theory, we can estimate that lower oxygen vacancy formation energy of amorphous LSC than La0.6Sr0.4Co0.2Fe0.8O3-δ can be the reason for faster oxygen reduction reaction kinetics of the heterostructured cathode. References (1) D. Ding, X. Li, S. Y. Lai, K. Gerdes, M. Liu, Energy Environ. Sci. 2014, 7, 552. (2) G. M. Rupp, A. K. Opitz, A. Nenning, A. Limbeck, J. Fleig, Nat. Mater. 2017, 16, 640. (3) Y. Gong, D. Palacio, X. Song, R. L. Patel, X. Liang, X. Zhao, J. B. Goodenough, K. Huang, Nano Lett. 2013, 13, 4340. (4) S. Y. Anthony, R. Küngas, J. M. Vohs, R. J. Gorte, J. Electrochem. Soc. 2013, 160, F1225. (5) H. J. Choi, K. Bae, D. Y. Jang, J. W. Kim, J. H. Shim, J. Electrochem. Soc. 2015, 162, F622. (6) H. J. Choi, M. Kim, K. C. Neoh, D. Y. Jang, H. J. Kim, J. M. Shin, G. Kim, and J. H. Shim, Adv. Energy Mater. 2018, 1802506

Resume : Silver nanowire (AgNW) network that possesses unique advantages in electro-optical performance, mechanical flexibility, and solution-processed manufacturing has been considered as the next generation of transparent conductive electrode (TCE) with the most potential in commercial development. However, it faces many difficulties during this process because its unique percolated structure encounters completely different problems compared to the traditional transparent oxide conductors in the practical application of optoelectronic devices, such as the defective electro-optical properties, large surface roughness and poor patterning performance. Therefore, the rational design of network TCE becomes ever so crucial targeting to different optoelectronic applications. We will introduce the optimization of such AgNW network based TCE from finite element simulation, which explores the electrical and optical properties of TCE theoretically, to the experimental skills, which include precise AgNW diameter control, aligned structure fabrication and water-mist assisted cold welding of junctions. As a results, these AgNW TCEs with excellent unique properties were applied in different fields, for example, the dual-mode electronic skin which integrates the functions of tactile sensing and visualized injury warning,[1] the high-efficiency semitransparent perovskite solar cells with the power efficiencies up to 16.03%,[2] and the flexible quantum dot light-emitting devices with 16.5% external quantum efficiency.[3] References: [1] ACS Appl. Mater. Interfaces 2017, 9, 37493. [2] Adv. Funct. Mater. 2018, 28, 1705409. [3] Adv. Opt. Mater. 2018, 6, 1800347.

Resume : Because of the leakage current due to reduced gate oxide thickness, a gate oxide material with high dielectric constant is required. HfO2 is one of the most promising gate dielectrics, and the thickness should be controlled precisely for the application. Nano-scale HfO2 films with nominal thicknesses of 1.2, 2.5 and 5.0 nm were prepared, respectively, on silicon substrates by ALD and used for thickness measurement RRT using XRR. 4 NMIs (National Metrology Institutes) and 12 ordinary laboratories participated. Aims of the RRT were to compare the HfO2 thicknesses, and to confirm international equivalence of nano-film thickness. Measured XRR curves were analyzed by simulation and fitting procedures, and the thicknesses were determined. Both thickness results and measurement uncertainties were reported from 4 NMIs, but only the thickness results were reported by 12 laboratories. Using the 4 NMIs results, comparison reference values and standard uncertainties were determined by the uncertainty-weighted mean method. The standard uncertainties of the film thicknesses were very small, i.e., 0.003, 0.007 and 0.012 nm, respectively, and the thickness result for each specimen from 4 NMIs was equivalent based on the expanded uncertainty of 95% confidence level. In addition, the thickness results from 12 laboratories were also equivalent to the results of NMIs for the corresponding specimens, assuming the similar uncertainty levels to the NMIs’. The results reveal that nano-scale HfO2 thicknesses determined by XRR from different laboratories are not only consistent with each other, but also extremely accurate. Furthermore, the fact shows that XRR is an appropriate measurement method for the thickness of nano-scale HfO2 film.

Resume : The effects of elastic anisotropy of austenite on the transport of nitrogen and carbon in austenitic stainless steel (ASS) during the expanded austenite formation are analyzed by the presented kinetic model. The model is based on the thermodynamics involving the anisotropic lattice expansion due to interstitial solute insertion. The stress induced by the concentration gradient of interstitials inside a solid affects the transport of interstitials in steel volume, i.e. elastic field is capable of creating an additional component of the driving force for the solutes transport. The anisotropy in elastic modulus of ASS results in anisotropic strain and stress in the supersaturated austenite phase during nitriding (and carburizing), which leads to an anisotropic stress assisted diffusion of interstitials. Furthermore, anisotropic surface energies of different oriented crystals lead to anisotropy of interstitials adsorption process. A consequence of these effects is that the thickness of the nitrided (carburized) layer depends on the crystalline orientation and the diffusion rate is found to be highest for (100) orientation. The theoretical results obtained on the basis of this model are qualitatively consistent with the available experimental data for polycrystalline and single crystal of ASSs.

Resume : Multilayer coatings consisted of alternative nitride layers of CrN/ZrN and pure metal layers Cr/Zr were deposited on the steel substrates using vacuum-arc evaporation of cathodes. Such composition allows depositing of combination of relatively soft and hard layers, combining in one complex coating. Various methods of analysis, such as XRD, SEM, EDS, TEM, HRTEM, SAED, RBS, SIMS, as well as hardness and tribology tests, were used for coatings characterization. Microstructure of the coatings is presented by cubic CrN and ZrN phases with (200) and (111)/(200) preferential orientation respectively. Hardness tests revealed maximal hardness of the coatings close to the value of 29 GPa due to Hall-Petch strengthening effect, and it is much higher compared to single-layer CrN or ZrN coatings. Good tribological properties in combination with excellent physical-mechanical properties makes a deposited material promising for application as protective one for machines and tools operating under extremely harsh working conditions.

Resume : Understanding and predicting the structure formation in polycrystalline, sputter deposited thin films of only few nanometers thickness is a great challenge. The thin film growth conditions are typically far away from thermodynamic equilibrium, resulting in complex microstructures with coexisiting phases, grain boundaries, and competing textures. To access the different aspects of structure formation, a combination of simultaneous and real-time X-ray reflectivity and X-ray diffraction measurements at the synchrotron, and lab-based UHV surface characterization studies was established. After a short introduction into the experimental approach, several examples for the time-dependent structure development during sputter deposition of nitrides and silicides will be given. These include non-reactive, reactive, and off-normal deposition processes, and the instant response of the structure formation on growth parameter changes. The experimental measurements are complemented by ballistic transport simulations of the angular and energetic distribution of the deposited atoms. The strengths and limitations of this approach will be discussed for different aspects of thin film growth, such as interface formation, multilayer deposition, and 2D vs. 3D structure formation. Some of the limitations can be overcome by combination with in situ stress measurements, which will be demonstrated on the metal/silicon interface formation.

Resume : In presented work we investigated the real structure and thermal evolution of niobium nanoparticles. Studied nanoparticles were prepared by magnetron-based gas aggregation cluster source (Haberland type GAS) from high purity Nb target in argon atmosphere. The phase composition, morphology and the real structure of nanoparticles i.e. the size and shape distributions, lattice parameters, lattice defects and size of coherently diffracting domains were investigated by combination of small angle x-ray scattering, x-ray diffraction and electron microscopy. In order to describe the thermal stability and evolution of nanoparticles, a critical issue for all its elevated temperature applications, the in-situ SAXS and XRD experiments were performed under the air atmosphere up to 800°C. As prepared, spherical nanoparticles with mean particle size of 21.6 nm contained pure bcc Nb phase in the core with thin 0.9 nm oxide shell at the surface. The size of coherently diffracted domains corresponds to the mean nanoparticle size, which implicates that at initial state each nanoparticle is formed by one crystallite. At the temperatures up to 200°C the phase composition and internal structure of nanoparticles does not significantly change. Above 200°C the amorphisation of nanoparticles occurs consequently followed by nucleation and creation of crystalline niobium oxides at around 450°C. The detailed description of thermal evolution of microstructural parameters is shown and discussed in our work.

Resume : Porous ZnO is often employed in (bio- and gas-) sensing and as host material for biomedical applications, such as drug delivery and tissue engineering. In novel biosensors technologies, such as lab-on-a-chip microdevices and nanosensors, nanoporous ZnO is especially desired as thin film, in order to meet the device requirements of conformality and thickness control. However, classical thin films technologies often suffer from an intrinsic low surface area and lack of framework porosity. In this contribution, the synthesis of nanoporous ZnO thin films is demonstrated through annealing of hybrid Zn-based polymers (zincone) obtained by molecular layer deposition (MLD). The zincone layers are deposited through MLD adopting diethylzinc and ethylene glycol. Nanoporous ZnO thin films were obtained by calcination of the zincone layers up to 600 °C. The removal of the carbon linkers, development of controlled and tunable nanoporosity, and formation and growth of ZnO crystallites were followed in situ during calcination by spectroscopic ellipsometry, X-ray diffraction (XRD) and reflectivity (XRR). The combination of the in-situ methods allowed the identification of temperature windows for the formation of pores (110-150 °C) and ZnO crystallization (340-450 °C). Ellipsometric porosimetry was adopted to characterize the ZnO open porosity and pore size distribution (PSD). Mesoporous ZnO layers were delivered with controllable porosity in the range 13-20% as a function of the calcination temperature, with a PSD between 3 and 6 nm.

Resume : Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) is a scanning probe approach to optical microscopy and spectroscopy bypassing the ubiquitous diffraction limit of light to achieve a spatial resolution of 10 nm. s-SNOM combines the best of two worlds, the nanoscale spatial resolution of Atomic Force Microscopy (AFM) and the analytical power of optical spectroscopy. It employs the strong confinement of light at the apex of a sharp metallic AFM tip to create a nanoscale optical hot-spot. Latter can be exploited for any wavelength from the visible light to the THz-region. Analyzing the scattered light from the tip enables the extraction of the complex dielectric function (absorption, reflectivity) of the sample directly below the tip and yields nanoscale resolved optical images simultaneous to topography. It allows chemical identification of nanocomposite materials, local free-carrier profiling in doped semiconductors and revealing structural and electronic properties in thin films and photo-active materials with monolayer sensitivity. This novel imaging and spectroscopy tool can sense structural information on polymorph materials like pentacene thin films and reveal stress-strain fields in semiconductor crystals, with unmatched spatial resolution. We extended s-SNOM also towards ultrafast pump-probe experiments with down to 10 fs temporal resolution. Relaxation dynamics of photoexcited carriers in an InAs film or the phase transition of VO2 can be observed.

Resume : Unexpected transrotational nanostructures [1] are studied by transmission electron microscopy (TEM) bend-contour method [2] for crystals growing in thin (10-100 nm) amorphous films of different chemical nature (primarily vacuum evaporated oxides, chalcogenides.) HREM, AFM were also used. The unusual phenomenon is observed in situ in TEM during local e-beam heating/annealing: regular rotation of the lattice orientation (dislocation independent internal bending of crystal lattice planes) is revealed in a growing crystal. Such transrotation (translation of the unit cell is complicated by small rotation realized round an axis lying in the film plane) can result in strong regular lattice orientation gradients (up to 300 degrees/µm) of different topology. The possible mechanisms of the phenomenon are discussed. Initial amorphous state and surface nucleation of the crystal growth are most essential factors. The last fact accompanied by anisotropy of crystal growth rate and tendency for regular change of interatomic distances of the crystal propagating from the surface layers inside the bulk material resembles specific epitaxy, “vacuum epitaxy”. The transrotation phenomenon is prospective for novel lattice-orientation/rotation, topological and strain nanoengineering of functional, smart thin-film. Transrotational micro crystals have been eventually recognized for some thin film materials vital in applications, e.g. phase-change materials for memory devices [3-4], ferroelectrics. [1] V.Yu. Kolosov and A.R. Tholen, Acta Mater. 48 (2000) 1829. [2] I.E. Bolotov and V.Yu. Kolosov, Phys. Stat. Sol. 69a (1982) 85. [3] B.J. Kooi and J. T.M. De Hosson, J. App. Phys. 95 (2004), 4714. [4] E. Rimini et al, J. App. Phys. 105 (2009), 123502.

Resume : Thin metal films deposited from the vapor phase onto weakly-interacting substrates show a pronounced 3D morphology during early stages of film growth, resulting in a higher surface roughness and smaller grain size as compared to films that display a 2D growth morphology. This is detrimental to the performance of the films in many technological applications, where they are being used due to their outstanding electrical (e.g., Cu contacts in microelectronic devices) and optical properties (e.g., low emissivity Ag coatings on glass). Surfactants are deliberately used to manipulate the homo- and heteroepitaxial growth of metal films on strongly-interacting substrates, however, a systematic study of this concept for weakly-interacting metal/substrate systems is still missing in the literature. Here, we study the influence of two species of surfactants (Cu, Ti) on the growth morphology of sputter deposited Ag thin films on weakly-interacting SiO2 in ultra-high vacuum, by employing in situ spectroscopic ellipsometry. Increasing the content of either surfactant in the film leads to a decrease of the continuous film formation thickness, indicating a shift towards 2D growth, which we confirm with real-space imaging of the surface with AFM and SEM microscopies. Furthermore, we examine at which stage of film formation the surfactants unfold their positive influence on the morphology and show that i) smoother film growth is ensured by adding the solute elements during the deposition of the first monolayer of film material, ii) delayed addition of the surfactant leads to opposite trends: a film roughening in case of Ti and a smoothening in case of Cu. These effects are being discussed with regards to the intrinsic surfactant mobility, and affinity to the film/substrate atoms. With knowledge of these effects, it becomes possible to engineer the film’s properties according to the needs of specific applications.

Resume : Dynamic processes at the liquid/solid interfaces are of key significance across broad areas of technological interest, such as solidification, liquid-phase epitaxial growth, wetting, liquid-phase joining, crystal growth, and lubrication [1,2]. Many studies have been reported with the indirect evidence of density fluctuations at liquid/solid interfaces on the basis of X-ray scattering methods [3], atomic force microscopy (AFM) [4] and with the support of atomistic simulations [5]. Transmission electron microscopy (TEM) can, in principle, allow us to observe dynamic processes directly, yet to date such investigations are scarce due to the exceptionally high need of an elegant microscope and a suitable system that enables to see liquids, solids and their junctions simultaneously. Hence, due to the lack of direct experimental observations at the atomic-scale and also for the intricacies of tackling such challenging systems, much confusion still exists regarding the atomistic understanding of the dynamic processes at the liquid/solid interfaces. Bismuth (Bi) bulk metal has a low melting point of 544.4 K and the melting temperature of its nanoparticles can be low even to room temperature due to size effects. As such, Bi is an ideal model material to track electron-beam induced nucleation and growth. Hence we take this unique system comprising of the formed Bi droplets on crystalline SrBi2Ta2O9 support and by manipulating electron doses within the TEM we probe such a liquid/solid interface. In this work, we observe the in-situ atomic-scale behavior of fabricated Bi droplets segregated on SrBi2Ta2O9 by using aberration corrected transmission electron microscopy. We demonstrate ordered interface and surface structures for the droplets on the oxide at the atomic-scale and unravel a nucleation mechanism involving droplet coalescence at the liquid/solid interface. We identify a critical diameter of the formed nanocrystal in stabilizing the crystalline phase and reveal lattice induced fast crystallization of the droplet at the initial stage of the coalescence of nanocrystal with droplet. Further sequential observations show the stepped coalescence and growth mechanism of the nanocrystals at the atomic-scale. Interestingly, in contrast to the rapid coalescence of two liquid droplets, the coalescence of a nanocrystal with a liquid droplet takes place via a clear step-migration mechanism. These results offer insights into the dynamic process at liquid/solid interfaces, which may have implications for many functionalities of materials and their applications [6,7]. The capability of performing such in-situ atomic-scale observations of dynamic processes of liquid droplets at a liquid/solid interface using advanced transmission electron microscopy represents a significant step forward in understanding liquids, solids and their interactions at the atomic-scale. These findings provide detailed dynamic information at the Bi/SrBi2Ta2O9 liquid/solid interface at atomic-scale, and should help to advance our general understanding of dynamic process in other liquid/solid interfaces. References [1] SH Oh et al, Science 310 (2005) p. 661. [2] OG Shpyrko et al, Science 313 (2006) p. 77. [3] H Reichert et al, Nature 408 (2000) p. 839. [4] S Biggs and P Mulvaney, J. Chem. Phys. 100 (1994) p. 8501. [5] GC Sosso, et al, Chem. Rev. 116 (2016) p. 7078. [6] J Li, Z Wang, FL Deepak, ACS Nano 11 (2017) p.5590. [7] J Li, J Chen, H Wang, N Chen, Z Wang, L Guo, FL Deepak, Adv. Sci., 2018, 1700992; DOI:10.1002/advs.201700992.

Resume : One of the great challenges in engineering science is to protect a material at its surface from chemical reactions and mechanical degradation such as high temperature oxidation, impact and wear. Applying a hard coating, which bonds strongly to the surface of the material, prevents excessive abrasion and provides the needed shield towards mechanical impact. At high temperatures in an oxidative environment, however, many hard boride, carbide and nitride coatings quickly deteriorate due to thermal instability and chemical degradation. An overview is presented of our recent efforts under the materials genome initiative to develop a new class of protective ceramic coatings, coalescing computational investigation and experimental realization and characterization. The efforts focus on several transition metal quaternary (Zr,Hf,Si)BCN and ternary (Hf,Ta)SiN amorphous and nanocomposite coatings for severe environment applications. Compositional and structural atomistic simulations using density-functional theory and large-scale molecular dynamic calculations were conducted to explore thermal, oxidation and mechanical properties. A number of complementary experimental characterization techniques were used to study the thermal, mechanical and oxidation resistance of the coatings. Atomistic and local structure characterization and image simulations were conducted by using HRTEM to develop a comprehensive understanding of the synthesis-structure-property relationship.

Resume : The synthesis of chromium nitride is a textbook case to study the magnetron sputtering process, its characteristics (DC, HiPIMS, bipolar …) and the influence on the final properties of the film. The improvement of the mechanical properties is often targeted, and achieved by an increase of the ionization level (from target materials or gas phase). This is generally achieved by pulse deposition (MPP, HiPIMS), modification of the magnetic field (balanced and unbalanced close field magnetron), or addition of features in the chamber (additional solenoid, Ar beam …), whereas the modification of reactive gas is hardly ever considered. In this view, the use of ammonia (NH3) as reactive gas appears to be a potential alternative to nitrogen (N2) to produce CrN films, due to the presence of hydrogen as potential source of ionisation. We thus studied the bipolar sputtering of chromium targets in presence of Ar/N2 and Ar/NH3 atmospheres. The influence of the two reactive gases in the sputtering process has been investigated through hysteresis curves. In situ measurements of the discharge parameter (target voltage, current and power density) in addition to optical emission spectroscopy (OES) and deposition rate measurement is reported, underlying the influence of hydrogen presence. Then, films have been synthesized in both atmospheres, and the physico-chemical, the structural, the optical and the mechanical properties fully characterized (XRD, XPS, RBS, UV-vis spectroscopy, resistivity, and nanoindentation). While the structural and optical properties of the films are similar, an improvement of the mechanical properties is obtained, with an increase of the hardness from 11.3 to 18.2 GPa and an increase of the Young modulus from 152 to 164 GPa.

Resume : Transition metal carbides (TMC) are known for their excellent thermo-mechanical stability, but their use in structural or thin film applications is limited by their poor fracture tolerance. Therefore, enhancing their fracture toughness, while retaining other thermo-mechanical properties is desirable for increasing the use of TMC in any application. One conceptional approach is non-metal alloying, involving the exchange of C by N or vacancies on the non-metallic sublattice. Based on its high thermal stability as well as hardness Ta-C is used as a base system. Ta-C thin films were synthesized via non-reactive sputtering, while ternary Ta-C-N coatings have been deposited in N2/Ar gas mixtures. Based on ab initio calculations, we could experimentally verify that structural defects, especially Ta vacancies, stabilize the preferred cubic structure for high N contents. Furthermore, our DFT results predicted a softening of the films (confirmed by nanoindentation) and an increase of ductility—according to the Pugh’s criterion—with increasing N content. During uniaxial compression of superhard (43.3 GPa) 110-oriented Ta0.47C0.34N0.19 pillars, we observed yielding at 16.9 GPa followed by plastic deformation where we identified {111} <011 ̅> as the most active slip system. From micro-cantilever tests, we determined KIC values of 2.9 compared to 1.8 MPa√m for Ta0.47C0.34N0.19 and Ta0.55C0.45 respectively, indicating that Ta-C-N exhibits indeed superior fracture tolerance compared to Ta-C.

Resume : The presentation deals with the structure, microstructure, mechanical and tribological properties and oxidation resistance of WNx films with a stoichiometry x=[N]/[W] ranging from 0 to 1.5 prepared by magnetron sputtering. The as-deposited films exhibit high hardness H=22–34 GPa and (1) columnar microstructure and α-W phase at x≤0.20 or (2) fine-grained microstructure, and a mixture of α-W and β-W2N phase at 0.200.1 and low k up to 0.01×10-6 mm3/Nm at T ranging from 22 to 150 °C, and (3) the WO3 surface scale with columnar microstructure created at T increasing from 150 °C to 500 °C acts as an lubricant where μ decreasing to ≈0.5 due to its low HWO3=4–5 GPa but k increasing above 6×10-6 mm3/Nm due to its low H/E*WO3=0.05.

Resume : Hard and tough tissues with exceptional protective capability designed by nature exhibit usually complex hierarchical micro/nanostructures and multiscale interfaces between alternating structural features differing in their crystalline orientations and composition. This is also a reason why it is so difficult to mimic microstructural and mechanical characteristics of natural materials in application-relevant synthetic nanostructures. In this contribution, synthesis routes for nanoceramic thin films designed with a variety of interfaces and hierarchical levels of various functional properties resulting in enhanced mechanical stability will be discussed. The hierarchical biomimetic films were synthetized using adapted physical and chemical vapor deposition techniques. In order to correlate the crack propagation behavior with the overall hardness, fracture stress and toughness values, in-situ micro- and nanomechanical testing was performed in scanning and transmission electron microscopes. The results indicate that by using dedicated self-assembly strategies, it is possible to design nanostructures, which exhibit simultaneously intergranular, transgranular and cleavage fracture modes with tortuous fracture paths at multiple length-scales resulting in exceptional mechanical properties. Additionally, in-situ high-temperature synchrotron X-ray diffraction analysis indicate that the interface design promotes the microstructural and phase stability of the films. In summary, the complementary experimental data document that multiscale interfaces are favorable for the mechanical and thermal properties of nanoceramic thin films.

Resume : Superhard protective multilayer CrN/MoN coatings were studied with consideration of their further perspectives as a solution for critical raw materials (CRMs) problem. Wear performance and lifetime of CrN/MoN films were estimated by measured hardness, Young’s modulus and calculated H/E ratio. They were ranked and compared to existed hard coatings with available information about their service time. Main regularities of microstructure formation and its impact on mechanical properties of CrN/MoN films with periodically changing architecture of layers were considered. Coatings were deposited by vacuum-arc evaporation of the cathodes (Arc-PVD) in nitrogen atmosphere. Two main nitride phases of CrN and γ‑Mo2N with fcc lattices with [311] preferential crystallographic orientation and nanocrystallites size of 5.5-17.2 nm were observed. Multilayer CrN/MoN films show high hardness of 38-42 GPa with H/E ratio of 0.11. Their strong wear resistance and long lifetime turn them to be a key solution for CRMs problem in industrial applications.

Resume : The few-layer MoS2 films are potential candidates for ultra-thin lubricants in high-temperature ultra-high vacuum (UHV) applications. Generally, the nano-tribological properties of thin films depend on a combination of their surface morphology and surface chemistry. Studying the impact of each of these two effects separately is experimentally challenging. In our work, we prepared few-layer MoS2 coatings with similar morphology but different orientation of crystallographic c-axis. The ‘lying-down’ and ‘standing-up’ phases of MoS2 showed similar surface roughness as measured by AFM. However, the orientation of c--axis altered the friction coefficient on nanoscale as measured with LFM (lateral force microscopy) and confirmed by macroscopic contact angle measurements. We showed that the crystallographic orientation of few-layer MoS2 thin films has fundamental effect on its nano-tribological properties.

Resume : In this presentation, by “large area” we will mainly refer to architectural glass, with substrate sizes of roughly 20 square meters. This market is characterized by large volumes and small margins, which has a strong impact on technology development. We will illustrate some of these consequences. Currently off-line coating is dominated by (reactive) magnetron sputtering. But in the last few years, a new – at least for the large area segment – technology came into focus: Plasma enhanced chemical vapor deposition (PECVD). This class of processes has many advantages compared to conventional sputtering techniques, including the possibility to deposit oxide films at a high rate from cheap raw materials with a low demand for electrical power, and in consequence low overall cost. Considering these benefits, it has taken a surprisingly long time until PECVD became available for large area deposition. The advantages, difficulties and reasons for the slow progress will be discussed. At the same time, new modified sputtering techniques have been developed. Specifically we will present the serial co-sputtering method, and its application in the development of new materials for switchable electrochromic coatings. Furthermore, we will discuss sequential sputtering processes, in which the deposition of the film forming metal and its oxidation are separated. This leads to excellent thickness control, making this technique well suited for optical coatings.

Resume : The structuring of functional materials is essential for the technological development of microelectronic components and applications. In this respect, we will introduce novel micro- and nanostructuring processes for PVD techniques such as MBE or electron beam/thermal evaporation. We have developed two methods for bottom-up growth, which are characterized by changing the roughness of the underlying substrate: The first method uses a shadow mask for minor pre-roughening (less than 10 nanometers), the second method uses mild surface transformations via femtosecond laser treatment. These surface and roughness modifications induce controlled self-organization and self-assembly processes. The basic description of the underlying mechanisms of micro- and nanostructure formation is also part of our research. In this case, both the local growth of the material and the area-controlled collapse of a thin film of the given material is possible. First applications of these methods are large area arrays of indium microislands on molybdenum and gold nanodroplets on silicon and silicon/silicon oxide wafers. These simple systems are to be transformed into more complex systems of functional materials. The indium islands can be arranged in a regular way and are converted into CIGSe islands for micro-concentrator energy conversion cells. Gold nanodroplets can be used to create silicon/germanium nanowires for thermoelectric applications.

Resume : The pyroelectric effect describes dependence in some materials between their spontaneous polarization and the temperature. This allows converting temperature variation into electricity. We propose, in this work, an original method in order to convert light into electricity using the pyroelectric effect. An anti-reflecting material the black-aluminum (black-Al) were deposited onto the surface of a stack structure of Pt/PZT/Pt in order to enhance light absorption. The structure black-Al/Pt/PZT/Pt demonstrated an effective conversion of the light into heat variation, and then the heat variation into a pyroelectric current. To prove it, a systematic comparison between a black-Al/Pt/PZT/Pt and a conventional Pt/PZT/Pt structure was performed. First of all, the electrical measurements showed a much larger variation of the polarization when a light was applied on the surface of the stack structure with black-al than without black-al. Then, a thermal camera clearly showed a larger temperature variation induced with the help of the highly absorptive of black-al layers. This result is very promising for future pyroelectric energy harvesting applications for nano-meters thick coatings.

Resume : Transparent electrodes are an essential component in most thin film solar cells as current-collecting electrode on the sun-facing side of the cell. Generally, they consist in an oxide thin layer presenting high transparency and good electrical conductivity. They can also present an additional function of haziness to improve optical absorption (through an increase of optical path) when integrated in thin films solar cells. A way to obtain such light scattering is to texture the TCOs, i.e. by increasing the surface roughness in order to enhance the ratio of the diffuse transmittance while keeping a high value of total transmittance as well as low electrical resistance. In this work, we will present the elaborations of new nanostructured and diffuse electrodes of fluorine doped SnO2 (D-FTO) in order to increase the light scattering in the visible range. This nanocomposite is obtained by combining successive depositions of periodic structures of nano-ZnO and optimized thin layers of FTO elaborated by Aerosol Assisted Chemical Vapor Depostion. The control of the ZnO nanostructure fabrication is made by using polystyrene nanospheres template of 500 nm diameter as template, recovered by a thin ZnO layer obtained by different chemical approaches: i) liquid method base on a Zn acetate solution ii) vapor method by ALD. Herein, we will compare the morphology and hazing character of the nanostructures and we will address the use of such composite nanostructured ZnO materials as TCO for photovoltaic devices. We will demonstrate how and why such nanostructured D-FTO materials reach requirements as transparent conductive oxides used in photovoltaics devices: 80% total transmittance with a high haze factor (20%) in the visible region, keeping a suitable sheet resistance value of 10-15 Ω/sq. Keywords: Transparent electrodes, transparent conductive oxide (TCO), FTO, haze factor, nanospheres of polystyrene

Resume : In classical magnetron sputtering deposition process, the target is heated due to bombardment by plasma ions, which induces an unwanted increase of its surface temperature and an emission of IR radiations [1]. To ovoid this effect and keep the magnets temperature below the Curie temperature (loss of their magnetic properties), the cathode is usually cooled using a water circulation. Some studies in USA [2] demonstrate that the grain size grows with the target temperature and roughness tends to decrease. A paper in the Lithuanian Journal of Physics [3] shows that Hot Target may promote a material phase and increase the deposition rate. To accomplish the “hot target” configuration, the target is thermally disconnected from the cooled cathode [4], for instance by adding a ceramic disk in between. By this way, the magnets are still cooled and the target surface temperature is able to rise, furthering the emission of IR light that can be adsorbed by the growing film. We studied the effect of IR emission on the characteristics of metal or oxide films, exhibiting with various IR absorptivity. In that aim, we compare deposition performed in “cold target” configuration, then using an additional IR source and in “hot target” configuration for similar IR light emission. As a target, we used titanium for several reasons: it is non-magnetic, it can reach high temperature without melting and titanium oxides are well-known materials (as thin films synthetized were metallic titanium and titanium oxides). Thin films have been characterised by SEM, RBS and XRD analysis. SEM analysis revealed columnar, homogenous and slightly porous thin films with thicknesses ranging from 530nm (cold target) to 1420nm (hot target) for the same deposition time (with a power of 150W). As a result, we can conclude on a better deposition rate (from 3nm.min-1 to 18nm.min-1). From the XRD experiments, the TiOx thin films obtained at 150W with “hot target” are crystallised and constituted by crystallites without any preferred orientation, while with the “cold target” thin films seem to be amorphous. [1] H. Kersten et al., Vacuum 63 (2001) 385-431 [2] S. M. Aygün et al., Journal of Applied Physics 103 (2008) 084123 [3] J. Cyviene et al., Lithuanian Journal of Physics, Vol 44, No.5 (2004) 353-358 [4] G. A. Bleykher et al., Vacuum 132 (2016) 62-69

Resume : It is now widely recognised that alternatives to conventional conducting oxide transparent electrodes (such as tin doped indium oxide coated glass) are required to enable optoelectronic devices compatible with flexible substrates and low cost roll-to-roll manufacturing. To this end transparent electrodes based on optically thin silver films have already been shown to perform as well as conducting oxide electrodes in organic photovoltaics (OPVs). Silver is the metal of choice for transparent metal electrodes due to its high electrical conductivity, low optical loses and stability towards oxidation, although it is recognised that its high cost will necessitate recycling if it is to be used in cost sensitive applications such as OPVs. Copper is an attractive alternative to silver because it has a conductivity comparable to silver at 1% of the cost. This talk will describe how the higher optical losses in copper can be mitigated by micro-structuring, and how copper can be rendered as stable as silver towards oxidation in air without compromising its electrical properties. The excellent performance of copper window electrodes in high efficiency OPVs (benchmarked against devices using conventional conducting oxide electrodes) will show that the future is bright for copper as a metal for flexible, transparent electrodes for organic optoelectronics.

Resume : Titanium (IV) oxide (TiO2) is one of the most studied semiconductor photocatalysts for the degradation of organic pollutants because of its high chemical and thermal stability. However, the photocatalytic performance of TiO2 is limited by its wide band gap (3.2 eV), low quantum efficiency and high electron-hole pairs recombination rate. Several studies have been shown that photocatalytic activity of TiO2 can be improved by tailoring its morphology (thin films etc.)[1], doping with noble metals (gold, silver etc.)[2] and coupling with metal oxides. The coupling of TiO2 other oxides has received a great interest due to improved ultra-violet (UV) light absorbing ability and large oxygen storage capacity. In this study, we prepared columnar TiO2 thin film structure decorated with different oxide NPs by reactive DC sputtering method. The structure, morphology, and chemical state of the prepared hybrid thin films were characterized by HEM, TEM and XPS. To investigate the photocatalytic activity, the bleaching of the methylene blue (MB) under UV irradiation was monitored by UV-Vis spectroscopy. In addition self-cleaning behavior and UV sensing capability of prepared hybrid thin film structures have been studied systematically. [1] M. Z. Ghori, S. Veziroglu, B. Henkel, A. Vahl, O. Polonskyi, T. Strunskus, F. Faupel, O. C. Aktas, Sol. Energy Mater. Sol. Cells 2018, 178, 170. [2] S. Veziroglu, M. Z. Ghori, M. Kamp, L. Kienle, H. G. Rubahn, T. Strunskus, J. Fiutowski, J. Adam, F. Faupel, O. C. Aktas, Adv. Mater. Interfaces 2018, 5, 1800465.

Resume : Metallization of surfaces is of major importance for a wide range of applications, from micro-electronics, antennas to photovoltaic (PV) energy. We have developed innovative nano-layers as efficient patterning and adhesion layers for site-selective metallization. Two different approaches will be detailed in this talk. Our first approach uses grafted polymeric layers to improve the adhesion of metallized layer or to pattern metals on plastic substrates, especially 3D-printed substrates. When the metallization of polymer substrates is required, adhesion is a significant challenge. We have developed a process based on the covalent grafting of an interfacial polyelectrolyte layer between the plastic surface and the metal layer, replacing the rough interface obtained by usual pretreatments methods (e.g. chromic acid treatment or mechanical roughening). This method increases the final adhesion between the plastic surface and the final metal layer through interdigitation between the materials. It is also used to form patterns on substrates. Our second example utilizes self-assembled monolayers (SAM) as novel, simple and cost-effective methods for patterning transparent conductive oxides (TCO) in order to form solar cell’s metal grid by copper plating. The investigated chemistry and explored deposition parameters on Indium Tin Oxide (ITO) have resulted in highly hydrophobic surfaces with exceptional coverage of the TCO by the SAM. The resistance of the deposited layers to acidic plating conditions has been a challenge but deposited layers at optimized processing conditions have demonstrated excellent masking properties for Ni plating using an electrolyte with adapted composition.

Resume : Silver and copper are the dominant carrying elements in electronics, solar cells and in a diverse range of emerging applications including flexible transparent electrodes and biological and chemical sensors. For these applications these metals must be patterned by printing from costly colloidal solutions of nanoparticles, by selective removal of metal by etching using harmful chemicals, or by electrochemical deposition which is a chemical intensive and slow solution based process. This talk will describe a remarkably effective and unconventional approach for the selective deposition of copper and silver that is 1. scalable to any area; 2. fast because compatible with roll-to-roll printing and thermal evaporation; 3. inexpensive because it uses thin printed films of low toxicity and cheap compounds; 4. completely avoids metal waste and the use of harmful chemical etchants because metal is only deposited where it is needed; 5. leaves the metal surface uncontaminated; 6. compatible with both insulating and conducting substrates. This new approach is based on the finding that vapors of silver and copper do not condense onto thin films of certain organic compounds, so metal is selectively deposited only where the organic layer is not printed. The beauty of this novel approach lies in its simplicity and versatility, since vacuum evaporation of metals is a widely available deposition method, and the shape and dimensions of the features deposited are limited only by the printing technique.

Resume : The need of decorated glazed porcelainized stoneware tiles having high resistance to surface abrasion is increasing especially for high traffic places, namely, shopping malls, airports, train and metro stations, etc. In order to achieve this goal nanosized alumina was added to the opaque glaze used as final layer of porcelainized stoneware tiles. The reinforcing agent – nonosized alumina – was characterized in terms of present crystalline phases (XRD), particles morphology, chemical composition (SEM/EDS) and granulometric distribution (Coulter and DLS). The modified opaque glazes were applied by jet spraying, over un-fired ceramic tiles, as a final layer. The tiles were dried and fired with a cycle that simulates the industrially used. The sintered glazes thermal behaviour was accessed (DA and DTA/TG) along with the present cystaline phases (XRD), microstructure and chemical composition (SEM/EDS). The resistance to surface abrasion was evaluated by the PEI method according to EN ISO 10545-7. This test simulates the ceramic enamel degradation over time and measures the surface abrasion resistance of enamelled ceramic tiles and classify them according to their performance in the test. In the end the tile surface was visually inspected and classified, the sample mass loss was measured and small colour differences (CIEL*a*b* coordinates) were evaluated according to EN ISO 10545-16. The obtained results were correlated with the final enamel layer composition and characteristics. Acknowledgments The authors gratefully acknowledge the project CERU4 POCI-01-0247-FEDER-03392. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES.

Resume : Thin films are ubiquitous in our daily life from information and telecommunication terminals to solar cells and windows. In this work, we present a new application of them in the hardware security of the silicon devices. An optically active thin film of TiO2-Ti-TiO2 along with the IC (integrated circuit) electronics is utilized to protect the security ICs against attacks through IC backside. In this method, layers are deposited by RF sputtering system at room temperature on the IC back surface and characterized by ellipsometry spectroscopy and SEM image. The mentioned multilayer-film provides angular-dependent reflectivity in the infrared region; this property is used to indicate the violation of the IC back surface. The results are verified by electrical measurements on the IC structure in the way that a pn-junction on the circuitry side is assigned as a light emitting device (LE) and is forward biased. LE emits light in all directions into the silicon bulk toward the backside and the reflected light from the back surface is detectable by another pn-junctions which are located on the circuitry side in different intervals from LE and are driven in reverse bias in the task of detectors. Absorbed light in the detectors creates a photocurrent and measuring the current of detectors gives us information about properties of the coated layer on the backside. In this technique, integrity of IC backside is verified by checking angle-dependent reflectivity of the layers.

Resume : Lithium niobate LiNbO3 (LNO)-based Bulk Acoustic Wave (BAW) resonators fabricated by Smart CutTM technology have been recently proposed as possible future elements in wide-band filter circuits. According to studies, transferred LiNbO3 films require an annealing between 200 and 600°C in order to reduce the ion-implantation damages and recover the piezoelectric properties of the bulk material. Although there is no consensus on the recovery conditions, it is essential that electrodes inserted below the transferred LNO film remain stable up to these temperatures to avoid compositional and/or phase variations potentially able to reduce device performances. We evaluated aluminum, Si-doped aluminum, molybdenum, ruthenium and tungsten electrodes deposited on bulk X-cut LNO wafers and annealed at 400°C for 2h to simulate an average recovery condition. Materials and interface stability were investigated by electrical resistivity measurements, X-ray diffraction, scanning electron microscopy, and secondary ions mass spectrometry (SIMS). Aluminum, largely employed as electrode for low temperature-operating acoustic devices, demonstrated hillocks formation and remarkable interdiffusion, only limited by Si-doping. The stability of Mo and Ru electrodes is currently under evaluation. Tungsten electrodes, however, proved to be very compatible with LNO: no phase variations in W and LNO and no evidence of interdiffusion at the interface between these layers were observed by SIMS analysis.

Resume : A tungsten oxide (WO3) nano-rod thin film by thermal oxidation for hydrogen sensor is presented in the research. A tungsten (W) film is deposited on a silicon dioxide by sputtering and then thermally grows in a furnace to obtain a WO3 nano-rod. Both oxidation temperature and pressure are chosen to be the parameters to reach a best WO3 nano-rod thin film for hydrogen sensing. The structural properties of the film are observed through X-ray diffraction analysis (XRD) and field emission scanning electron microscopy (FE-SEM) and the optical property of the film is evaluated by PL spectrum analysis. The growth of WO3 nano-rod depends much on the growth temperature. The WO3 nano-rod becomes obviously at the sample of 650 and 750 °C growth, while the growth of the nanorod is being limited as the temperature increases to 850 °C. XRD shows the intensity of WO3 (002) increases with the growth temperature from 550 to 750 °C, and decreases at the 850 °C growth temperature. The PL analysis shows that a lot of defect energy states exist in the WO3 crystal, the emission intensities locate in the region of 618~639 nm. The hydrogen sensibility is strengthen by the growth of the nano-rod, and it shows a sensibility of 1.2 at the sample of 750 °C.

Resume : Low operation temperature of solid oxide fuel cell (SOFC) is crucial to improve the reliability and durability. The interface between cathode and electrolyte materials plays an important role to improve the cell performance and lower the operation temperature. We employ a nano-web-structured La0.6Sr0.4Co0.2Fe0.8O3-? (NW-LSCF) thin-film layer at the interface between the La0.6Sr0.4Co0.2Fe0.8O3-? (LSCF)- gadolinium doped ceria (GDC) cathode and GDC electrolyte using a facile spin-coating method. This functional layer could increase the triple phase boundary length and enhance the adhesion strength between LSCF-GDC cathode and GDC electrolyte, which leads to significant improvement in the electrochemical properties even low operation temperature of 550oC. The cell with this functional layer exhibits peak power density over 500mW, which is 60% enhanced value compared to that of cell prepared without the functional layer. The effect of the functional layer was also verified through electrochemical impedance spectroscopy.

Resume : Introduction We propose two-layered thin film architecture and its fabrication method based on industry-compatible processing techniques. The strategic approach includes a combination of polymer embedded quantum dots (QD) film coated with an additional oxide layer. This assembly offers an increased photo-thermal stability and provides a simple architecture for various luminescent thin film based applications. Results and Discussion Quantum dots, a nanometer sized crystallites, offering high intensity photoluminescence are a promising material for absorbing and converting light energy applications. However, they are very sensitive to the environmental conditions and their degradation presents major challenges. Many of the most promising technological applications of luminescence require thin films. Film deposition technology is well-established in industry with a number of different techniques used for the manufacturing of both polymeric and inorganic thin films. From industrial point of view, the fabrication of QD-polymer composites and their high quality thin films is extremely relevant and despite many advantages, this development has been inhibited by incompatibility of QDs with polymeric environments. We addressed these issues and developed a system that presents many opportunities for possible industrial applications of QD-based materials. We proposed a straight forward solution for incorporation of colloidal QDs into polymer without any modifications to the synthetic route or luminescent properties deterioration, directly providing a simple and cost-reduced formulation that can be employed in thin film fabrication. Further studies focused on the evaluation of the QD-polymer thin film long-term optical efficiency, ultimately leading to the introduction of an additional protective coating. The oxide layer, acting as a barrier, was processed via plasma assisted ALD technique directly onto QD-polymer film, which allows to maintain the continuity for the large scale processing. An extensive study was undertaken where the degradation trends of both, the non-coated and oxide coated QD-polymer film samples, were assessed under accelerated aging conditions, including high intensity illumination (150 mW/cm2), an increased temperature (85?C) and humidity (85%). Highlighting the impact of each parameter, the evaluation was performed based on the luminescence quantum efficiency deterioration as a function of exposure time. The analysis showed that, even under the most demanding conditions, samples with protective layer have retained their photoluminescence stability at 80% of the original level over the period of 300h, whereas the unprotected ones, have dropped to 30% after 75h. Conclusions The study indicated that the introduction of a dual encapsulation system for QDs has significantly extended their operational lifetime. The polymer material has a two-fold functionality providing both, mechanical and chemical stability to the QDs, as well as the role of the matrix material, whereas oxide layer acts as a direct barrier against external environment.

Resume : Nanocrystallization is a promising way to improve the photonic properties of group IV materials by increasing the optical transition probability and additional control of the optical gap by quantum confinement effects. Ge nanocrystals (NCs) in oxide matrix offer some advantages in comparison to the Si alternative because of spectral extension in IR, confinement effect in bigger NCs and low thermal budget for nanocrystalization. The oxide matrix plays an important role in NCs formation, as well as in electrical and photonic effects in such composite materials. Therefore, exploring different oxides, using different deposition techniques is of high interest. In this work we investigate the Ge NCs in TiO2 obtained by magnetron sputtering co-deposition of Ge and TiO2, on Si and Ge wafers covered by thick SiO2. The annealing at 550oC resulted in the formation of Ge and TiO2 NCs, as revealed by HRTEM and XRD. The conductance at room temperature is controlled by thermal activation of electrons from Ge NCs to the TiO2 matrix, and by Efros-Shklovskii hopping at lower temperatures. The optical absorption limit is shifted by electron confinement to about 1 eV. The spectral photoconduction measured in a coplanar geometry has an important contribution from the substrate by surface photovoltage and gating effects. Thus, in comparison to Si substrates, the spectral sensitivity of Ge NCs is extended to longer wavelength of about 1.8 µm for Ge substrates.

Resume : Here we demonstrate that it is possible to realize color-filter-free, full-color, thin-film (<800 nm) organic photodiodes (OPDs) and their image sensor arrays by employing a novel electrode structure, “etalon-electrode,” which has dual functions of electrode and wavelength selective window. In other words, we have developed a novel R/G/B organic image sensor pixel of a new diode architecture that combines a dual functional thin-film etalon-electrode and a thin-film panchromatic organic photodiode, to realize color filter-free, narrowband full color-detection (full width at half maximum <100 nm) as well as high detectivity (D*>10^12 Jones). Furthermore, because this new “etalon-electrode” strategy enables facile patterning of R/G/B pixel arrays by adjusting the thickness of constituting layers within etalon structure, we could demonstrate a color image capturing ability of organic image sensor without color filters. We also added more detailed results and related descriptions, such as transmittance spectra as a result of the introduction of anti-reflection layer, ideality factor analysis, noise current plot for calculating specific detectivity, dark current and detectivity distribution of unit OPDs in a 10×10 R/G/B OPD array. We believe that this technique can be one of the breakthrough for the realization of ITO-free, color filter-free, thin film and color selective OPD.

Resume : The front window layer of thin film silicon solar cells should serve a number of functions, such as high transparency, high conductivity and anti-reflection nature. In this paper, we report a comprehensive study on the effects of p-type window layers on thin film silicon solar cell performance parameters. Silicon based single layers and the total p-i-n single junction silicon solar cells were continuously grown in a conventional cluster-type five-chamber PECVD deposition system (13.56 MHz rf power supply) at 300 °C and 0.7 mbar on various substrates from precursor gas mixtures. All the single layers of the cells were deposited on Si (100) and quartz substrates for optimization before applying in solar cells. XRD, Raman, FT-IR, UV-Vis and ellipsometric spectroscopy were employed to investigate the structural and optical characteristics of prepared single layers. We introduced different p-type layers as front window: boron doped amorphous silicon carbide layers (~ 1.9-2.1 eV), amorphous silicon layers (~ 1.7-1.8 eV) or their combination (multilayers). The grids were printed using Aerosol Jet printing technology. A conductive ink based on silver nanoparticles (Clariant TPS50) was printed to the form of grids. The employed cells have an area of 1cm2. To characterize the cells, automated J-V curve and EQE measurements were performed under standard test conditions (1000W/m2, 25°C, AM1.5G spectral distribution).

Resume : The main objective of this work is to take advantage of the specificities of Zinc Oxide (ZnO) Nanowires (NWs) coatings (porosity, specific surface?) for LED lighting and photocatalytic applications. In the former applications, these coatings are associated to Ce3+-doped yttrium aluminum garnet (Y3Al5O12 :Ce or YAG :Ce) nanophosphors. The alliance ZnO NWs / YAG :Ce is expected to enhance the optical performances of luminescent coatings through improved light extraction combined with the unique optical properties and contribution of ZnO NWs (red emission, diffraction effects, antenna effects, ?).. For photocatalytic applications, ZnO NWs coatings serve as host matrix for titanium dioxide (TiO2) nanoparticles (NPs) to develop functional composite coatings able to degrade organic pollutants. In this presentation, we will describe the controllable growth of one-dimensional ZnO nanostructures, using a sol-gel / hydrothermal synthesis combination, and we will investigate their properties as diffracting networks which are subsequently impregnated with sol-gel synthesized YAG: Ce NLs or TiO2 NPs. Then, we will presents the structural, morphological and optical characterizations of these composite coatings. Their photoluminescence and photocatalytic properties will finally be presented and discussed to highlight the positive contribution of ZnO NWs in their association with YAG: Ce or TiO2 NPs.

Resume : Platinum is known to be the reference catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cell. Further enhancement of the Pt catalytic activity while reducing its amount inside the fuel cell is one of the main issues for practical application of these systems due to the limited abundance of Pt on Earth. Various preparation processes on novel Pt catalysts should be proposed. Magnetron sputtering is able to produce active Pt based catalysts on porous electrode [1] but the process is difficult to combine with conventional ink preparation techniques based on chemical processes. A solution consists to synthesize Pt nano-catalysts directly in liquid phase using vacuum magnetron sputtering technique [2] even if the growth mechanisms are not completely well-understood [3]. This innovative method takes advantages of the extremely low vapor pressure of liquid such as ionic liquid, vegetable oil and silicon oils [4] compatible to vacuum techniques. In this study, PdPt and Pt nano-catalysts have been grown in vegetal glycerin liquid into a vacuum sputter apparatus based on a DC 2 inches magnetron. The size of the nanoparticles and their dispersion have been tuned by varying deposition parameters as the argon pressure (from 1 to 9 Pa), the magnetron power (from 13 to 100 W) and glycerin temperature (from -6°C to 27°C). We follow the evolution of the cathode voltage during the growth which gives insight into the nanoparticles growth mechanisms. Nanoparticles with a size ranging from 2 to 5 nm assembled in highly ramified networks are synthesized in liquid whereas a thin film can be observed on its surface in some cases. Catalyst supported on carbon (typically Vulcan) was obtained by filtration, washing, and drying and was characterized by hydrogen adsorption/desorption (cyclic-voltammetry) in order to the measure the electrochemical surface area (ESA). Finally 5 cm² 10%wt Pt/C electrodes were prepared and assembled in PEM fuel cell. This work has been supported by The Region Centre Val-de-Loire through the Lavoisier INPACT program. [1] M. Mougenot et al., International Journal of Hydrogen Energy 36 (2011) 8429-8434 [2] T. Tsuda et al., Journal of Power Sources 195 (2010) 5980–5985 [3] X. Carette et al., J. Phys. Chem. C, 122 (2018) 26605–26612 [4] H. Wender et al., Coordination Chemistry Reviews 257 (2013) 2468-2483

Resume : In this work Cu2O thin films were prepared by magnetron sputtering on silicon and quartz substrates and characterized by Raman and Fourier-transform infrared spectroscopy (FTIR). A promising material for thin film solar cell application is cuprous oxide (Cu2O). Cu2O thin films were deposited on 10×10×0.5 mm3 substrates by reactive DC magnetron sputtering, in various flow gas pressure conditions. Deposition with magnetron sputtering is one of the standard ways for PVD microelectronic technologies, which allows to prepare layers with a controlled stoichiometry. The main magnetron sputtering techniques are: constant (DC), alternative current - Radio Frequency (RF), and pulsed mode using either a metallic or composite target. Non-polarized micro-Raman spectra were collected in retroimpeded geometry with a LABRAM HR 800 spectrometer using an excitation laser source of 632.8 nm from 150 to 900 cm-1. The FTIR spectra of Cu2O thin films deposited on Quartz substrate present a transmission peak at around 617 cm-1, which was attributed to the Cu(I)-O vibrations, for all the samples. The peak corresponding to Cu(I)-O vibrations was more visible comparatively to the films deposited on Si substrate.

Resume : For this study, multilayered hybrid materials consisting of alternating ZnO and phage layers have been fabricated in order to achieve a structure, which mimics the one of natural composites such as nacre. Since nacre and many other natural composites are known for their outstanding mechanical properties, our research is aiming at an artificially designed material which possesses enhanced mechanical strength compared to the pure constituents. For sample fabrication the following bio-mimetic approach was used: the deposition of M13 wild type phages on silicon substrates was achieved using the convective assembly technique; ZnO layers were deposited from a precursor solution at ambient conditions. In this way multilayer samples with varying thicknesses of the individual layers could be produced. The mechanical properties have been extracted from nanoindentation testing. For structural analysis SEM and STEM investigations were performed. In order to gain a better understanding of the deformation mechanisms in these hybrid materials, we performed indentations to different penetration depths and with various tip geometries. The microstructures in the deformed state were investigated with STEM. The results, which will be presented reveal the deformation mechanisms within the multilayers and correlate the microstructure to the mechanical properties.

Resume : A novel technique for the selective growth of ZnO nanorods is established, by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) and hydrothermal growth. Various ZnO nanorod arrays were obtained on silicon substrates, by UV-NIL of ZnO seed patterns with lines of 200 nm wide at a pitch of 1000 nm from a photosensitive ZnO precursor, followed by a selective hydrothermal growth step with varied growth times. It was found that the aspect ratio of ZnO nanorods increased from 2.7 to 11.8 as the growth time was increased from 2 to 6 h. It was also found from TEM analysis that the ZnO seed layer consists of both tiny crystallites of random orientation and amorphous phase. The crystallites on the surface provide nucleation sites for hydrothermal growth, resulting in single crystalline ZnO nanorods with a preferred (002) growth. An isotropic radial assembly of nanorods was observed from cross-sectional SEM images and this growth results in the nanoflower-like structure of the nanorod arrays on the patterned ZnO seed. This technique offers an alternative method for integrating ZnO nanorods at low temperatures and free of high vacuum, potentially useful in applications such as nanophotonics, photovoltaics and flexible nanoelectronics.

Resume : This work focuses on the investigation of morphology, structure, Er ion related defects and emission of ZnO:Er nanocrystal (NC) films obtained by ultrasonic spray pyrolysis with the different Er contents and post-annealing. The scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) methods were used. It is revealed that the crystal structure of ZnO:Er NCs can be improved at low Er-doping (≤ 2at%), when the Er ions occupy the Zn vacancies in ZnO NCs with the formation of the substitutional ErZn defects. Simultaneously, the PL intensity of near band edge (NBE) emission enlarges and PL intensity of green PL band connected with native deep defects decreases. Meanwhile, the IR emission via the 4f intra-shell optical transitions (4I13/2- 4I15/2 ) in the Er ions at this condition is insignificant. PL intensities of NBE emission, all visible and IR bands related to the 4f inner-shell optical transitions in Er ions, have enlarged essentially at higher Er-doping (<5at%). It is revealed by XPS that at this Er content the process of Er ion oxidizing is realized. This Er concentration can be considered as an optimal for the bright Er ion emission owing to Er oxidizing and the formation of a low symmetry oxygen environment around of Er ions. Further enlarging the Er content provokes ZnO crystallinity falling down together with the formation of native defects in ZnO NCs and PL intensity decreasing. It is expected that deep understanding the Er-doping process in ZnO NCs will be useful for the strategy development to obtaining ZnO:Er NC films with tailored parameters.

Resume : As member of carbon materials family, CNTs and graphene are distinguished materials that can be combined with functional materials such as nanoparticles (NPs) or organic semiconductors to target specific application (sensors, energy, adsorption etc.). Such an association identified as surface engineering (functionalization or decoration) allows to build functional hybrid materials with excellent properties derived from the combination of the carbon material properties and the functional material properties. For sensor applications, such hybrid materials fabrication allows to finely tune the nanomaterials composition via surface engineering to reach unique sensing performances. However, sometimes because of incompatibility between the surface engineering and the sensor realization, the surface engineering is realized ex situ and therefore coating methods have to be developed. With progress in thin film realization, the sensing devices can be prepared by thin film technology (dropcasting, dip coating, Langmuir-Blodgett, spin coating etc). The nanosized hybrid materials made from CNTs or graphene are processable as thin films for sensors application. Here we will show how the proper functionalization of CNTs or graphene via surface engineering combined with thin film technology, can be used to realize sensors dedicated to pollutant detection (NO2, BTX, NH3 and H2S). Sensor performances and materials characterization (TEM, SEM, TGA etc.) will be also presented.

Resume : We fabricated twistable, rollable, foldable, and bendable polymer-oxide-metal multi-layered hybrid films that act as a multi-functional electrode for flexible polymer-dispersed liquid crystal (PLDC) windows and flexible and transparent thin film heaters (TFH) for self-cleaning and flexible smart windows. By using continuous sputtering of a thin polytetrafluoroethylene (PTFE)-ITO-AgPdCu (APC) multilayer on a colorless polyimide substrate (CPI), we demonstrated multi-functional and transparent hybrid films. The hybrid films have a high optical transmittance of 83% at a wavelength of 550 nm, low sheet resistance of 7 Ohm/square, high contact angle of 109, and low transmittance in the infrared region. Through lab-made rolling, inner/outer bending, folding, and twisting tests, we demonstrated the mechanical properties of flexible PTFE / ITO / APC multi-layered films. Flexible PDLC and TFHs with PTFE/ITO/APC multi-layered electrodes showed a controlled transmittance range between the turn on and off states of nearly 40%, and high saturation temperature of 111 °C was examined at low applied voltages of 4V. Fabricated from PTFE / ITO / APC hybrid film on CPI substrate, the multi-functional properties of the flexible PDLC and TFHs indicate that the polymer-oxide-metal hybrid film is a multipurpose transparent electrode that can be used for self-cleaning, energy saving, and smart window.

Resume : Ga-doped ZnO (GZO) graded layer, which facilitates electron extraction from electron transport layer (ETL), was integrated on the surface of transparent ITO electrode by using graded sputtering technique to improve the performance of planar perovskite solar cells (PSCs). The thickness of graded GZO layer was controlled to optimize GZO-ITO combined electrode apt for planar PSCs. At optimized graded thickness of 15 nm, the GZO-ITO combined electrode showed an optical transmittance of 95.41 %, a resistivity of 2.27×10-4 Ohm-cm, a sheet resistance of 15.68 Ohm/square, and work function of 4.23 eV, which is well matched with LUMO level (4.0 eV) of PCBM. Due to enhanced extraction of electron by the graded GZO, the PSC with GZO-ITO combined electrode showed higher power conversion efficiency (PCE) of 9.67 % than the PCE (5.25 %) of PSC with only ITO electrode without GZO graded layer. In addition, the GZO integrated-ITO electrode act as transparent electrode and electron extraction layer (EEL) simultaneously due to graded mixing of the GZO at the surface region of ITO electrode.

Resume : Dip pen nanolithography (DPN) is a scanning probe nanolithography technique where an atomic force microscope (AFM) tip is used to transfer molecules or nanoparticles to the surface of a substrate in a controlled manner. In DPN technique, the ink material to be patterned is transferred from the coated tip / meniscus to the substrate surface / meniscus. Comparing with micro printing (µCP or Inkjet printing), DPN printing method provides a greater flexibility because it allows control over the size of the pattern by adjusting the tip speed dwell time and environmental control. Through this technique features with sub - 100 nm resolution and precision has been patterned. Further, DPN technique has more advantages over other scanning probe nanolithography techniques: the equipment improves the ink transfer, doesn’t need a restricted environment (as does electron beam lithography), and it can be carried out under ambient conditions. Using a multi-probe array, DPN can printing different inks simultaneously. Another advantage is the possibility to immediately analyses the deposition quality by Lateral Force Microscopy (LFM). Dip - pen nanolithography technique can be used to create self - assembled monolayers (SAMs) on the substrate, with great selectivity, to deposit in a controlled manner: small organic molecules, biological molecules, polymers, conductive polymers, biopolymers and macromolecules. Also, hard materials can be deposited in a desired pattern: metal, semiconductors, inorganic sol precursors, nanoparticles catalyst, etc. In this paper we present fabrication of metallic electrodes using DPN by direct deposition of self-assembled monolayers of molecular ink. The metallic nanoparticles (gold, silver and copper) were synthesized and printed on substrate. The quantitative studies were addressed to optimized the adsorption and assembly of ink molecules onto the surface (relative humidity, the physicochemical properties of the ink). The effect of print quality and SAMs formation were investigated by morphological and electrical methods. The conductivity measurements will be presented to affirm the reliability of the electrodes. This direct writing patterns of metallic thin film paves the way for use this technique in printable electronics and circuit repair technique.

Resume : Rare earth doped upconversion materials have great potential in laser, optical communication, three-dimensional display, biomedical and other fields. However, the main mechanism for obtaining rare-earth upconversion luminescence is energy transfer up-conversion (ETU) and cooperative sensitization upconversion ( CSU) and energy migration upconversion (EMU), etc. We have recently successfully constructed an interface energy transfer (IET) luminescence model that enable luminescence of Er3+, Tm3+, Ho3 +, Tb3+ , Eu3+ , Dy3+ , Sm3+ and Nd3+ rare earth ions. The model is also applicable to the Nd3+ -Yb3+ double sensitization system, which can achieve up-conversion luminescence at 808/980 nm dual-wavelength excitation in a single particle. By further constructing the IET process of multi-layer nanostructures, Yb3+ -A3+ (A = Er, Tm, Ho), Gd3+ -A3+ (A = Tb, Eu) and Nd3+ -Yb3+ and other rare earth donors are realized. This energy transfer process is precisely regulated at the nanoscale. These advances not only provide a new way to achieve upconversion luminescence, but also benefit the development of new and efficient upconversion luminescent materials.

Resume : Colors and decorations are essential features to improve the esthetic appearance of a material and are also significant for the perception and identification of both natural and artificial objects. As the application fields of metals rapidly extend into consumer electronics, art, decoration, and building interior, their esthetic appearance becomes more and more important. While pigment-based chemical colors can be easily faded by environment, structural colors are resistant to fading and also look more esthetic. We here show that vivid structural colors can be produced on bulk stainless steel. The structure consists of a thin dielectric layer coated on the textured surface of stainless steel. Diverse colors could be produced simply by changing the thickness of the dielectric overlayer. The colors result from the surface plasmon resonance and guided mode resonance of incident light, which occur on the metal surface and inside the dielectric layer, respectively. Simulation based on the finite-difference time-domain method supported the experimental results, showing that the layer thickness influences the characteristic wavelengths of both resonances and the resulting colors. We also demonstrate color laser printing on the surface of stainless steel, where the thickness of a solution-coated SU-8 overlayer was locally controlled with a ultraviolet laser beam.

Resume : The close resemblance of hydroxyapatite (HA) to the bone mineral, as well as the ease of fine tuning its functional response (e.g. osteoconductivity) by designed ion-substitutions, made it a material of choice for numerous biomedical applications. It has been stressed the prominent role of HA dielectric features on the biomedical performance (i.e. application of electromagnetic fields can accelerate the healing of bone fractures). HA’s piezoelectricity was advanced as explanation, but this is incompatible with its hexagonal structure. The engineering of HA dielectric properties by intentional compositional and structural alterations could be an alternative, but remained to date mostly unexplored. Lithium could constitute an interesting HA dopant, being able to allow not only the decrease solubility and boost of bone fracture healing, but also to change its dielectric response. In this work, the influence of physical-chemical features on the dielectric properties of simple and Li-doped synthetic and biological (BHA), in both bulk and sputtered film form, has been explored. SEM, EDXS, XRD, FTIR and impedance spectroscopy measurements were carried out. For the films, the structure and dielectric constant were strongly anisotropic and lower in value with respect to the bulk state. Their differences were explained by the different (a-axis or c-axis) preferred orientation. The results showed promises that the application horizon of HA-based ceramics could be expanded.

Resume : Selenization process is fascinating the attention of many researchers because this is very attractive for electronic, optical, thermoelectric fields. It is a type of annealing process and usually used as essential technique for a wide range of formation of dense thin films. However, the commonly used methods for selenization have limitations of toxic of H2Se gas and high temperature, so poor extendibility into various applications. And also, while selenium induced changes in the properties of absorber layers have been well studied, the concept of Se source changing for selenization has rarely been examined. Herein, we demonstrate the alternative cost-effective, facile one-step and one-zone selenization process and successful preparation of new Se source by mixing Al2O3 with Se for the selenizaiton of Cu2GeS3 thin films at even low temperature . And, detailed investigations were conducted to explain the influence of Al2O3 on the thermal behaviors and stabilities of Se in Se-Al2O3 samples, such as increasing of the surface area of the Se powders. And also, we examined the mixing ratio-controlled influence of Al2O3 with Se from only Se to Se-Al2O3 mixed powders during the selenizaiton. In result, mixing of Al2O3 with Se can induce new melting and vaporization properties of Se and as a result influence the selenizaiton behavior of the Cu2GeS3 thin films. So, this process can broaden applicability by easily controlling the band gap of various chalcogenide materials and thin films.

Resume : As the development stage of organic semiconductor technology is approaching to commercialization, eco-friendly process for organic semiconductor is getting increasing attention. Up to now, water-borne nanoparticle of organic semiconductor via miniemulsion process has been widely used for such eco-friendly process. Nonetheless, opto-electronic performances of water-process organic devices are still inferior to their organic-solvent-processed counterpart. The biggest issue for the success of water-borne organic semiconductor is how to handle large amount of residual surfactants, which is used as stabilizers for dispersing organic semiconductors, because they can induce micro-scale aggregation and low charge carrier mobility. Here, we report a new surfactant engineering technology for water-borne organic semiconductors which enables to reduce the amount of surfactant by controlling the adsorption ability of surfactant on water-borne nanoparticle. Based on the optimized water-borne ink of organic semiconductors, we realize high performance organic field effect transistor and organic photovoltaics, comparable to those processed with organic solvents

Resume : Fouling organisms have perplexed researchers for thousands of years, most of antifouling strategies were onefold and harmful to non-target organisms, efficient and environmentally friendly antifouling methods are still a goal in pursue. In this study, a series of acrylate boron fluorinated polymers (ABFPs) were synthesized. The molecular structure was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR), the special surface microstructure and antifouling mechanism of ABFPs were investigated and verified by SEM, XPS and Static contact angle. Antifouling properties were investigated by diatom anti-settling assays and real-sea test. The results showed that the coatings made of ABFPs have a very good antifouling performance in the Bohai Sea of China during 90 days. These can be explained that after the hydrophobic side groups hydrolyzed, the resulting forming hydrophilic groups migrated to the polymer surface to form a hydration shell which can prevent the fouling organisms from attaching to surfaces.

Resume : Slippery liquid-infused porous surfaces (SLIPS) inspired by Nepenthes, also known as super-repellent surfaces, has attracted extensive attention due to their wide variety of practical applications. Despite extensive progress over an intense research, these current super-repellent surfaces are still hampered by problems: limited storage capacity of lubricant and inability to self-healing after lubricant loss in a certain area. Herein, we describe a strategy to create slippery liquid infused fibrous porous surface (SLIFPS) with exceptional storage capacity and storage stability of slippery liquid. In this work, we use water-soluble non-woven fabrics with different formulas as sacrificial templates to build fibrous porous surfaces with average pore size of 15µm. The effect and retention of lubricant on the fibrous porous surfaces are investigated and discussed. The capability to repel various liquids (such as deionized water, coffee, fruit juice, hydrocarbons, algae broth and blood) and to restore liquid-repellency (contact angle hysteresis less than 5°) after lubricant loss in a certain area or physical damage of SLIFPS was also demonstrated. We assume that fibrous pores provide spaces and channels for the storage and flow of lubricant. Our results suggest that using fibrous porous surface substrates that lock the infused lubricating fluid in situ can solve for the poor storage capacity of lubricant and inability to self-healing. We foresee a wide range of applications in liquid delivery, medicine, adhesion control, self-cleaning surfaces, anticorrosion and antifouling materials. (This paper is funded by the International Exchange Program of Harbin Engineering University for Innovation-oriented Talents Cultivation.)

Resume : We present a facile and low cost method of utilizing the anodized aluminum oxide of the pore size of 13 nm and the microsized silicon membrane of the pore size of 2 ?m as a reproducible template. Both templates were stacked together and they were vacuum infiltrated by poly(dimethylsiloxane) resin to prepare poly(dimethylsiloxane) adhesives of a hierarchical micro-nanopillar that can be used as dry adhesives. Compare to adhesives that containing only micrometer-size fibrils, the hierarchical structure adhesives exhibited a higher adhesion force. A normal adhesion force of 8 N/cm2 were observed on the glass substrate, which were larger than that of homogeneous poly(dimethylsiloxane) micropillars. The successful fabrication of the dry adhesives of the hierarchical structure can be potentially used in applications requiring large scale reusable adhesives, such as pick and place tools, medical tapes and climbing robots.

Resume : Nowadays Oblique Angle Deposition (OAD) by magnetron sputtering method has received an increasing popularity as it gives an opportunity to tailor film architectures and control film properties, as micro-structure, texture, porosity, anisotropy. In the case of Transition Metal Nitrides (TMN), sputter-deposition results in the formation of columnar thin films, but predicting their micro-structure remains challenging as the influence of the deposition parameters is not fully understood. In this framework, a set of thin films of TMN (TiN, HfN, ZrN) was deposited by reactive magnetron sputtering on Si (001) substrates inclined at different tilt angles α=5°, 65°, 75°and 85° with respect to the surface normal of the target material. The morphology of the layers and microstructural properties, such as crystal structure, texture, grain size, were studied for a working pressure of 0.3Pa at 300°C. Two analysis techniques were used for the structural and microstructural characterization of these thin films: Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The microstructures analyzed in SEM are columnar. Moreover, the SEM analysis showed that the angle of inclination β of the columns of HfN increases between 2° and 34° with the increase of the substrate tilt angle α, and the variation is similar for ZrN. This analysis also showed that the porosity of the layers increases with the increase of α and that the thickness of the layers decreases with α. XDR pole figures were made for the crystallographic planes (111), (200) and (220) to determine the texture of these thin films. A study of electrical properties was also done by measuring the resistivity of the layers using Van der Pauw's four-point method. The evolution of β versus α will be discussed for the three material systems and compared to existing empirical laws and those simulated from a kinetic Monte Carlo (kMC) model [1]. [1] B. Bouaouina et al., Mat. & Design 160 (2018) 338 Key-words: thin films, metallic nitrides, scanning electron microscopy, X-ray diffraction, GLAD.

Resume : Particle arrangement has been used for microfabrication processes and it is known to be quite useful for making various structures in nano and micro scale on a substrate. Nanoparticles in liquids, or colloids, have advantages that their distribution is uniform in liquid and their motion follows the fluid flow. However, for the microparticles, their inertia is not ignorable at all and the particles are influenced more by gravity. Meanwhile, Most of the particles are carried in liquid droplets in microfabrication processes. So understanding of inner flows of a droplet is also required, which are caused from capillary force, Marangoni effect or coffee-ring effect. And when the droplet evaporates, profile, or the shape of the droplet itself comes to be another important parameter. In this study, experiments were performed using microparticles in a water droplet. And the variation of the profile during evaporation was investigated, which is strongly related to the arrangement of the particles after the evaporation. Furthermore, experiments were done for upward and downward droplets, respectively, so that the direction toward gravity could be inverted.

Resume : Silicon dioxide is proven a solution for numerous applications. Besides the common dielectric and insulating properties, or use as a gas diffusion barrier, SiO2 can be utilized in tuning the mechanical properties of thin films. SiO2 has been made with several different ALD chemistries, all with pros and cons. Issues with chloride impurities have led to the use of amine precursors. In addition, the >300C deposition temperatures have been proven too high for sensitive substrates, and can cause interlayer diffusion at interfaces. PEALD[1] as a solution has low throughput and limited conformality, and common processes, such as bis(diethylamino) silane and ozone, the growth rate at 100C is only < 0.1Å per cycle [2]. Therefore, a low temperature thermal process with industrially viable growth rates is needed. We present a novel low temperature SiO2 process with growth rates >1Å per cycle from 60 to 350C, on single wafers and in batches, using a precursor with 3 Si atoms and an amine group. While the film thickness increases linearly with the number of cycles, other properties will need to be a compromise between film quality and deposition temperature. The experiments were made with PICOSUN™ R-200 Adv, P-300B and P-1000 hot-wall ALD systems. Si wafers with native oxide layers were used as substrates. The ALD process, its scalability to larger batches, and various properties of the resulting thin films were evaluated in this study. [1] Won et al. (2010) [2] Hirvikorpi et al. (2010)

Resume : The availability of the latest thin film deposition techniques allows gradual down-scaling of semiconductor devices. Especially when depositing films on pattern, the thermal or plasma-enhanced atomic layer deposition (PE-ALD) system outperforms conventional deposition processes in terms of step coverage and film uniformity. However, the PE-ALD films grown on the patterned sidewall need to improve their properties compared to those on flat surface due to the relative difference in plasma exposure time. Fundamental studies on the plasma treatment starting from blanket film are essential to understand and improve the film quality on patterned sidewall. In this work, we present the detailed experimental results of plasma treatment effect on the silicon dioxide (SiO2) film grown by PE-ALD. The thickness of the film was determined by Spectroscopic ellipsometry. To characterize the chemical composition, Fourier transform infrared spectroscopy and Elastic recoil detection analyses were performed. In addition, wet etch rate (WER) and electrical properties were evaluated. In our results, films with short in-cycle plasma duration exhibited a growth-per-cycle (GPC) of 1.7 Å and a WER of 6.5 Å/s. However, for films with longer plasma time, significant decreases in GPC, WER, dielectric constant and leakage current were observed. Corresponding decrease in the H content of about 35% was detected, also indicating the correlations between GPC, WER and electrical properties.

Resume : Wounds may become complicated by associate diseases, chronic conditions and infection. In the design of efficient wound healing, improved wound dressings are recently being investigated. The purpose of this study was to obtain bioactive antimicrobial nanostructured materials through laser processing for improved wound dressings. Chitosan coated silver nanoparticles were deposited by Advanced Laser Processing (MAPLE = matrix assisted pulsed laser evaporation) on commercial wound dressings. The obtained nanostructures and coatings were characterized by y transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected area electron diffraction (SAED), differential thermal analysis– thermogravimetry (DTA–TG), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. Qualitative antimicrobial evaluation was done by an adapted agar diffusion method. For the quantitative measurement of biofilm embedded microbial cells, a culture-based, viable cell count method was used. In vitro cytotoxicity was assessed through the MTT assay on human diploid cells. Results demonstrated that the obtained nanoparticles and coatings have a great antimicrobial effect, inhibiting colonization and biofilm formation of wound-associated microbial pathogens in a time dependent fashion. The obtained nanocoated dressings proved a good biocompatibility and a prolonged antimicrobial effect in vitro, being efficient for up to 72h.

Resume : Controlling charge injection at metal-semiconductor interface is very crucial for organic electronic devices in general as it can significantly influence the overall device performance. Herein, we report a facile, yet efficient contact modification approach to enhance the hole injection efficiency through the incorporation of a high vacuum deposited TPD (N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine) interlayer between the electrodes and the active semiconducting layer. The device performance parameters such as mobility and on/off ratio improved significantly after the inclusion of TPD buffer layer and more interestingly, the devices with cost effective Ag and Cu electrodes were able to exhibit superior device performance than the typically used Au source-drain devices. We have also observed that this contact modification technique can be even more effective than commonly used metal oxide interface modifying layers. Our investigations demonstrate the efficacy of TPD interlayer in effectively reducing the interfacial contact resistance through the modification of pentacene energy levels, which consequently results in the substantial improvement in the device performances.

Resume : A full color, rewritable reflective mode display is presented, based on a novel self-assembled block copolymer (BCP) photonic crystal (PC) film combined with conventional ink-jet printing. A high resolution full structural color image is instantly developed when an ionic liquid ink is ink-jetted on a solid-state 1-dimensional BCP PC paper consisting of alternating lamellae one of which contains chemically cross-linked, interpenetrated network of a hydrogel polymer. The excellent susceptibility of the ionic liquid ink into the domains with the interpenetrated network allows for the localized swelling of the domains upon ink-jetting, giving rise to a variety of full colored SC images. Subsequent ink-jet printing successfully produces a new set of SC information on the paper, leading to a flexible, rewritable BCP PC display suitable for a variety of emerging applications for non-volatile information storage and display.

Resume : Optical modulators are a key component of photonic integration circuits (PICs), where these devices are required for tuning, reconfiguration and stabilization operations. Different physical processes can be used in order to manipulate the properties of an optical medium. In this work, a new approach for an optical modulator system is demonstrated. The device is based on the working performance of a solid-state lithium-ion battery, and the relation between the optical properties and the stoichiometry of mixed ionic-electronic conductor (MIEC) materials. It is implemented on PICS as waveguide coating, and actuates on light propagating through the waveguide-modulator system by electrochemically changing the composition of the MIEC material. To realize this modulator, a multilayer stack was sputtered and characterized forming a battery-like system where ions reversibly travel from a Li-ion source to a LixV2O5 coating layer producing the desired change of the optical properties. Modal field FEM simulations were carried out to estimate the influence of the formed modulator on a waveguide fundamental mode implemented on a silicon on insulator platform including different optical devices. Both simulations and measurements show promising results for a potential modulator system, like small device length (< 20 µm), low power consumption (~ 10 pW/modulation), reversibility and long-time stability.

Resume : The development of stress in vapor-deposited thin films is strongly correlated with the film morphological evolution, which is, in turn, controlled by the deposition parameters, including substrate temperature T and growth rate F. Metal films grown on weakly-interacting substrates at conditions of high atomic mobility exhibit a pronounced 3D growth. In situ and real-time measurements of residual stresses have shown that this is accompanied by a compressive-tensile-compressive stress evolution profile as a function of film thickness, which can – in combination with theoretical models and ex situ observations – be directly correlated with the stages of 3D island formation, coalescence and hole-filling, respectively. In addition, stress relaxation occurs upon deposition interruption as shown by numerous studies. However, there is no universal understanding of the way by which atomic mobility and energy of film forming species affect the stress evolution beyond island coalescence. In this work, we study in situ and in real-time the stress generation and evolution of sputter-deposited Ag and Cu films during and post-deposition on amorphous carbon, with F ranging 0.015 to 1.27 nm/s, and T between 298 and 354 K. We find a general trend towards less compressive stress formation with increasing T, for both systems. The stress-dependence on F is more complex: i) less compressive stress is formed when depositing Ag faster, ii) with increasing F, more compressive stress is formed during slow growth < 0.1 nm/s of Cu, iii) less compressive stress is formed when increasing F in the range > 0.1 nm/s. The post-deposition tensile stress evolution becomes less pronounced with increasing T and decreasing F, while it is kinetically faster with increasing F and T. These results are critically discussed with regards to the ex situ characterized film morphology, adding valuable insights to the processes governing stress formation and evolution in sputter-deposited films.

Resume : In this paper, we propose a new high performance ITO (Indium Tin Oxide) transparent electrode film design using plasmon resonance of metal nanoparticles that can offer the benefits of improved optical behavior and reduced resistance values. Our investigation shows that the proposed structure provides the possibility for modulating the conductivity in the ITO layer to improve the transparent electrode performances. This concept suggests achieving the dual role of an appropriate transparency behavior and enhanced resistivity values. Moreover, a new hybrid approach based on numerical simulation and metaheuristic Optimization is proposed to determinate the better compromise between the electrode transparency and resistivity of the amended transparent electrode film to achieve further optical and electrical enhancements. It is found that the optimized design exhibits superior performances. Therefore, the optimized transparent electrode film using plasmon resonance of metal nanoparticles paradigm pinpoints a new path toward recording high-performance transparent conducting electrodes for photovoltaic or flexible solar cells due to their low resistivity and high optical transmittance.

Resume : Multilayer nanostructured TisiN/TiZrN coatings with various bilayer thicknesses were fabricated using vacuum-arc evaporation of a cathode (CA-PVD method) under different deposition parameters, such as nitrogen pressure and bias potential. Microstructure and physical-mechanical properties of the deposited coatings were studied by XRD, SEM with EDS, SIMS, as well as by indentation and tribological tests. It was found, that decrease of the bilayer thickness led to increase of the physical-mechanical response of the coatings due to increase of interphase boundaries and smaller size of crystallites. First-principles calculations of the microstructure and internal stresses were conducted for deeper understanding of the influence of interphases on the structure and physical-mechanical properties of the multilayer coatings. Good correlation between experimental and theoretical results was obtained. The work was done under the aegis of the Science and Technology Center in Ukraine (STCU) within the project No 6372 entitled “A first-principle approach for the design of new superhard nanocomposite coatings” and from the Polish Ministry of Science and Higher Education as a statute tasks of the Lublin University of Technology, at the Faculty of Electrical Engineering and Computer Science, 8620/E-361/S/2018.

Resume : In recent years graphene due to its unique properties has shown to be an auspicious material for various electro-optical applications like photodetection, photovoltaics, transistors, ultrafast lasers and other applications. Control of the type and location of defects and their arrangement into ordered and extended structures becomes an important issue in creation of new graphene-based materials with novel properties. Despite negative connotations, understanding the influence of such defects on the carrier dynamics and excited state relaxation pathways is a key to modifying the optoelectronic properties of graphene-based devices. In our research we present ultrafast transient absorption technique as an efficient measure of quality of graphene layers. The excited state relaxation dynamics measurements (typical relaxation times, absorbance spectral dependences) were performed together with the electrical characterization, structural and morphological analysis. The analyzed graphene layers were deposited on copper foil and transferred on insulating substrates or directly deposited on the quartz substrate employing advanced microwave plasma enhanced chemical vapor deposition technique, which enables the synthesis of large area graphene. The detailed analysis and comparison of structural, morphological and electro-optical properties of graphene layers depending on preparation method was carried out by utilizing Raman scattering spectroscopy, AFM, SEM, XPS.

Resume : High-performance gas sensors based on ZnO quantum dot layer has been demonstrated. To enhance the sensor performance, soft-lithographic patterning of colloidal ZnO solution has been applied. Different pattern shapes, such as lines/spaces, pillars, amd recessed holes, can easily be fabricated using elastomeric stamps having different patterns. When compared to non-patterned, flat film of ZnO quantum dot, the patterned ones have shown much enhanced sensing performances, such as response, sensitivity, and response time. The origin of such performance improvement has been discussed based on various analytic results, such as photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), etc.

Resume : ZnO nanowires were synthetized using the VLS technique for the development of an optical biosensor to detect thiolated oligonucleotide probe labeled by cy5. The development of the two different morphologies of nanowires (i.e., random and straight orientation) was studied by scanning electron microscopy (SEM). After that, surface functionalization of both kinds of ori- entations of nanowires were carried out using thiolated oligonucleotide, and interaction mechanism between the DNA and ZnO nanowires were studied. Later on, surface enhanced Raman spectroscopy (SERS) and photoluminescence (PL) characterization techniques were carried out to study the transfor- mation induced on the optical properties as a result of the modified surface properties of the nanowires, and a brief comparison was carried out. The results could provide a good basis for the development of new type of optical biosensor for the detection of wide series of biological molecules.

Resume : Epitaxial ZrB2 thin films can be deposited using DC magnetron sputtering from a ZrB2 compound target on 4H-SiC(001), Al2O3(001) and Si(111) substrates[1-3], but epitaxial growth on Si(100) remains to be demonstrated. In this study, we use DC magnetron sputtering from a ZrB2 compound target to deposit ZrB2 thin films on Si(100). Epitaxial growth and substrate-film interface morphology were studied and the latter compared to previous results on Si(111), where the interface exhibits roughness and an amorphous layer complicating epitaxial growth[2]. Using pole figures, we ascertained that the films on Si(100) were epitaxial and in combination with θ-2θ diffractograms 2 epitaxial relationships have been found. Full width at half maximum values from rocking curve measurements of the (100) and (102) peak were used to obtain a measure of epitaxial quality for these 2 preferred orientations. Lattice parameters and strain values were determined from reciprocal space maps, and analytical high resolution electron microscopy results allow for comparing the morphology of these films to films grown on Si(111)[2]. [1]L. Tengdelius, E. Broitman, J. Lu, F. Eriksson, J. Birch, T. Nyberg, L. Hultman, and H. Högberg, Acta Mater. 111, (2016) 166-172 [2]L. Tengdelius, J. Birch, J. Lu, L. Hultman, U. Forsberg, E. Janzén, and H. Högberg, Phys. Status Solidi A 211, (2014) 636-640 [3]L. Tengdelius, G. Greczynski, M. Chubarov, J. Lu, U. Forsberg, L. Hultman, E. Janzén, and H. Högberg, J. Cryst. Growth 430, (2015) 55-62

Resume : Circulating tumor cells (CTCs) have emerged as novel tumor biomarkers and aroused a lot of interests on the unique information for the cancer patients. CTCs are mainly characterized by their immunostaining pattern which exhibit broad variation, so that accurate CTCs detection and profiling is still challenging in recent years. Matrix assisted laser desorption ionization time of flight mass spectrometry(MALDI-TOF-MS) is a soft desorption technique for biomolecule analyzing, due to its high sensitivity, rapid analyzing, and feasible sample preparation, it has been used for cell profiling based on lipid analysis. However, because of the interference of the conventional matrix ions, it is difficult to analyze molecules in low mass range (< 500 Da), which limits its application for cells detection. Therefore, we design and developed a TiO2 nanofiber micro-arrays on ITO glass for CTCs capture and further profiling by MALDI-TOF-MS in situ. TiO2 have strong absorption in uv range which is suitable for laser desorption, meanwhile we functionalized the rough surface of TiO2 nanofiber by epithelial cell adhesion molecule (EpCAM) increase the adhesion ability of the arrays to capture CTCs. The cells captured by TiO2 nanofiber arrays were detected by MALDI-TOF-MS directly. This method suggests potential for CTCs cell accurate recognition and further clinical applications.

Resume : Thin film systems find their applications in various fields from optics to hard coatings for large scale instruments. The combination of differently compounded films require precise control of materials properties and the analysis of these properties might be required to be performed depend on demand. For example, a smart residual stress distribution in a microscopically thin coating may significantly decrease coating failure probability and improve life time of a device. For such applications, investigations of residual stress fields in multilayers with high spatial resolution have become necessary. Our setup at P03 Nanofocus Endstation (PETRA III, DESY) is operated by Helmholtz-Zentrum Geesthacht and provides a highly stabile experimental setup with a high spatial resolution using a nanosized X-ray beam. It is one of only few places in the world where the experimental conditions for scanning X-ray nanodiffraction are provided and it offers a hard X-ray beam with a size of only 250 x 350 nm^2. In last years a number of successful experiments for ex-situ and in-situ multilayers coating studies were performed. In this presentation the setup for nano level resolution experiments at the Nanofocus Endstation of P03 beamline (PETRA III, DESY) will be presented with technical characteristics and results of successful users’ experiments will be shown.

Resume : Transition metals nitrides are a special category of conductive ceramics with unique properties, such as substantial electronic conductivity, exceptionally high melting point and tunable work function, and wide range of applications. Among them, titanium nitride (TiN) is recently emerging as significant candidate for plasmonic applications (biosensors, catalysis and photochemistry, solar energy harvesting, photo-detection, and optical storage of information). In this work, TiN nanostructures with controlled spacing and tunable dimensions were fabricated using Nanosphere Lithography (NSL) and DC magnetron sputtering (MS) or HIPIMS for the growth of TiN nanostructures. NSL appears as a very promising approach, due to its rapid implementation and compatibility with wafer-scale processes. NSL combines the advantages of both top-down and bottom-up approaches and includes: (a) preparation of the nanospheres colloidal mask and (2) the deposition of the desired material in the empty space between the spheres. The mask is then removed and the layer keeps the ordered patterning of the mask interstices. Specifically, a suspension of monodisperse polystyrene nanospheres (diameter, d=552 nm) was spin coated onto the Si (001) substrate and formed the mask. Subsequently, the selective growth of TiN was made by: (i) rf biased DC MS or (ii) HIPIMS, in Ar/N atmosphere by varying the TiN thickness from 10 to 30 nm. The arrays of ordered TiN nanostructures appear after the lift-off of the nanospheres mask. Atomic Force Microscopy showed growth of TiN nanostructures with d<20 nm, while Optical Spectroscopy and Spectroscopic Ellipsometry confirmed the TiN nanostructures plasmonic response in the visible spectral region. Ref.: P. Patsalas, N. Kalfagiannis, S. Kassavetis, G. Abadias, D.V. Bellas, Ch. Lekka, E. Lidorikis, Materials Science and Engineering R 123 (2018) 1–55.

Resume : Chromium nitride and oxynitride coatings were deposited as monolayers ((Cr–N), Cr(N,O)) and bilayers (Cr–N/Cr(N,O), Cr(N,O)/Cr–N) on 304 steel substrates by reactive cathodic arc method. The aim was to develop rough, large surface area, corrosion- and erosion-resistant coatings for 304 stainless steel mesh, used as support for powder photocatalysts, utilised in water remediation technologies. The coatings were characterized by XRD, SEM, EDS, surface profilometry, and scratch tester. The anticorrosive properties of the coatings were assessed by electrochemical tests in saline solution. Cr2N, CrN, and Cr(N,O) phases were identified in the coatings by GI-XRD measurements. The measured adhesion values ranged from 19 N to 35 N, the highest value being obtained for the bilayer with Cr(N,O) on top. Electrochemical tests showed that Cr(N,O) presence in both mono- and bilayered coatings determined the lowest damage in corrosive solution, compared to the Cr–N coatings, ascribed to the more compact structure, lower coatings porosity, and smoother surface. The bilayer with Cr(N,O) on top possessed the best corrosion resistance behaviour, having the lowest current density corrosion and consequently the highest protective efficiency and the lowest porosity. The corrosion resistance was ranked as: Cr(N,O) > Cr–N/Cr(N,O) > Cr(N,O)/Cr–N > Cr–N. We acknowledge the support of the Romanian Research & Innovation Ministry: 2019 Core Projects and Project PROINSTITUTIO - contract no.19PFE/17.10.2018.

Resume : In order to overcome depletion of fossil fuel, it is necessary to research alternative energy sources. In particular, hydrogen energy has been known as a future pollution-free energy source, and is being regarded as the ultimate fuel because of its various application field. Pt-group metal is commonly used as catalyst for hydrogen production. There are many study have been conducted to replace Pt-group metal catalysts because of its cost issue. Among the hydrogen production catalysts, MoS2 is considered one of the promising materials because it has high hydrogen bond energy and active site. In addition, TiO2 is known as a photocatalyst which has excellent wastewater treatment effect and excellent stability. In this study, we synthesized MoS2-TiO2 hybrid thin film for hydrogen evolution reaction. We conducted electrochemical characteristics, morphology analysis, and hydrogen quantification. Finally, we confirmed synergetic effect of MoS2-TiO2 hybrid thin film in terms of hydrogen production. This research was supported by the Nano?Material Technology Development Programthrough the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (2016M3A7B4904328).

Resume : The novel control method of corrosion protection for Al alloys using steam, steam coating, was applied to a couple of Al alloys. The resultant film was characterized and evaluated by electrochemical measurements. In particular, pitting corrosion behavior was investigated because this property of the alloys is particularly significant when they are applied as structural materials. This presentation was focused to discuss the development of a new coating technology that is environmentally friendly, and which thus contributes to the creation of a sustainable society. FE-SEM images of the film surfaces showed that plate-like nanocrystals were densely formed over the entire surface. XRD patterns indicated that the film was composed mainly of AlOOH crystals. The potentiodynamic polarization curves revealed that the corrosion current density of the film-coated substrates significantly decreased, and that the pitting corrosion was completely suppressed. The appearance of the surface of the film-coated specimen exhibited no damage at all, even after saltwater immersion for 48 h. In contrast, considerable pitting corrosion was observed on the as-received specimen. Even after immersion in a NaCl solution for 48 h, the pitting corrosion did not occur on the alloys that had been film coated using the steam coating method. In summary, the corrosion resistance of the film-coated Al alloys were improved, leading to the wider application of the alloy as structural materials. Acknowledgement: This research was supported by Japan Science and Technology Agency (JST) under Industry-Academia Collaborative R&D Program "Heterogeneous Structure Control: Towards Innovative Development of Metallic Structural Materials" (No. 20100120).

Resume : Since the first organic light emitting diode (OLED) in 1987 by Kodak, OLED technology has made its way into everyday life through smartphones, TVs and wearables. In contrast to the initial two-layer device, modern OLED stacks consist of multiple different layers which in case of the emissive layers are often a mixture of two to three different organic materials. These layers are usually manufactured either by physical vapor deposition (PVD) or by solution processing techniques, the former being the de facto industry standard. The resulting morphology governs many device properties but is not accessible by conventional imaging methods due to its light elements and amorphous nature. Here we show two different modelling approaches, which both aim to simulate the PVD process in order to acquire the lacking insight into the nanoscale thin film morphology. We compare a molecular dynamics model, with a classical bead-spring force field and time integration against a Metropolis Monte Carlo approach, where the intramolecular degrees are reduced to torsional rotations. Therefore, the computational cost and scalability as well as the density of the final film, which is available through experiment, are analyzed for different typical OLED materials. The developed methods are the basis for predictive computational device models which enable in silico molecular design.

Resume : Biopotential electrodes are crucial in modern preventive medicine, being the primarily responsible for high-resolution monitoring the bioelectrical activity of human body. In this work, flexible dry biopotential electrodes based on binary systems of Ti-Me (Me = Al, Cu, Ag, Au) thin films were developed for non-invasive physiological monitoring. These biopotential electrodes supported by polymeric bases aim to expand the applications of enhanced sensing in new opportunities, for better healthcare conditions. The Ti-Me thin films were prepared by DC magnetron sputtering without substrate heating. The use of a composite target (with different number of Me pellets) originated a wide range of chemical compositions and different thin film microstructures and physical responses. Working as bipotential electrodes, the Ti-Me thin films will be placed in direct contact with the skin and body fluids, which means that the materials selected need to be harmless and may not compromise skin integrity. The interaction of the Ti-Me thin films with skin cell models (fibroblasts and keratinocytes), was assessed in vitro for each system, studying their metabolic cytotoxicity and evaluating the oxidative stress. No evidences of Ti release to the medium was observed. On the other hand, the metal leakage from the Ti-Me films increased with the Me atomic content, for the generality of the films. Some oxidative stress was observed, proportional to the amount of Me present in the thin film. However, no significant damage in cell viability was noticed, with exceptions of some compositions of Ti-Cu thin films.

Resume : To quantify fundamental features of the coupling process between photons and surface plasma oscillations, various types of metallo-dielectric interfaces were intensively investigated. In the interest of enhancing significantly the sensitivity of the occurred transfer energy, in consequence, advantages of graphene layers and MoS2 were already been highlighted in several papers of the literature. In this contribution, we propose an other active material to substantiate the sensitivity of a designed biosensor that shows the ability of sustaining efficiently electromagnetic field generated during the coupling process by tuning structure’s parameters. To turn the limit of sensitivity, porous silicon carbide (P-SiC) has been considered between a glass-substrate of high refractive index and a nanostructured cavity (three stacked layers referred as MIM-waveguide). To understand the effect of porosity, the response of the proposed device is simulated by the transfer matrix formalism and where P-SiC, assumed as an effective meterial, is described according to the effective index theory (EIT). Thus, to evaluate the overall limit on the sensitivity, deduced from the angular-response probed on the sensing device, two types of models including the porosity are considered. In this theoretical analysis, all thicknesses, of the media involved, are turned at the subwavelength scale and the sensitivity was determined on both the change of refractive index of the sensing medium, I (surrounded by active materials) and its thickness. Finally, according to the results described on the electromagnetic field associated to the resonant coupled modes, the multilayer sensor based on the property of P-SiC, can be used as a suitable sensing platform to explore and confine efficiently resonant interface phenomena.

Resume : The development of sensors with low limit of detection and a specificity that can be easily tuned is still a challenge in the field of sensors. We present an original platform constituted of an engineered lipid monolayer which is used as the active sensitive layer and as ultra-thin gate dielectric in field effect transistor sensors. Supported lipid layers, with thicknesses of a few nanometers indeed constitute good candidates. In living cells lipid membranes are known to constitute natural insulators which play an efficient role as barrier to both ionic and electronic transport across the membrane, associated with an electrical resistance of the order of several giga-Ohms in magnitude. However, despite excellent insulating properties, lipid bilayers and even more lipid monolayers have been poorly exploited in devices due to their inherent instability under application of an electric field, leading to damages caused mainly by an electroporation process occurring at low electric field. Furthermore a lack of mechanical stability is often observed. We show that the mechanical and chemical stability of lipid layers as well as their dielectric performances can be improved by changing the molecular structure of the lipids and by achieving intra-chain reticulations within the layer, and that surprisingly both these properties are correlated. In fact such reticulated layers with a thickness of 2.5 nm only present low leakage current even at high electric field, and a direct dielectric breakdown occurring at ~30 MV/cm, i.e. much higher than for a silicon oxide layer of similar thickness or other high- dielectrics. We show that ones the lipid monolayer on the transistor channel the specificity of the sensor given by the grafting of probes to the lipids can be tuned using simple procedure making our sensor extremely versatile. As a proof of concept, we present here different sensors that were developed for the detection of Fe3+, Cu2+ and Cs+ ions using different materials, inorganic transistors with silicon channel and organic transistors with a Poly(3-hethyl)thiophen as channel, and different types of probes. Our sensors present good specificities with exceptional low limit of detection down to the sub-femtomolar range, high sensitivity and a linear response over several decades. Langmuir 26, 2538-2543 (2010). Patent: FR2983637/WO2013083490A1. Langmuir 27, 13643-13647 (2011). J. Phys. Chem. B 116, 7190-7195 (2012). J. Mat. Chem. B 1, 443-446 (2013). Biosens. Bioelect. 54, 571-577 (2014). Anal. Chem.(88) 3804-3809 (2016). Patent: PCT/EP2016/074569. Adv. Func. Mat. 10.1002/adfm.201801024R1 (2018) Funding: ANR-16-JTIC-0003-01 and SATT-Sud Est under contract N°147680.

Resume : This contribution presents our efforts to increase energy densities in supercapacitors while maintaining high power densities exploiting pseudocapacitance and nanostructuration. Combining transition metal oxides and nanostructured carbon materials in one electrode is considered as one of the best ways to achieve these performances. In this study, carbon nanotubes/graphene/manganese dioxide nanostructured thin films were designed as supercapacitors electrodes. MnO2 is a well-known pseudocapacitive material used to increase the energy density. Carbon nanomaterials generate high conductivity and large surface area to maintain a high power density. The challenge is to assemble these materials in a nanostructured electrode with controlled homogeneity, morphology, and composition. Our approach is to synthesize MnO2 by anodic electrodeposition directly onto a conductive nanostructured carbon framework. Mixing carbon nanotubes and graphene sheets can increases the accessibility by creating a controlled porous network in the electrodes. These carbon nanomaterials were deposited onto a current collector by dynamic spray gun deposition, an easily scalable, reproducible and industrially suitable method used for nano-structuration of thin films. Materials were characterized by SEM, XPS, microporosity, and electrochemistry. Results demonstrate that capacities can reach 190 F/g for binder free electrodes (1 mg/cm2) thanks to a strong control of the MnO2 morphology, particle size and Mn/C ratios.

Resume : Flexible polymeric substrates with multi-responsive nanorods capable of pressure, temperature and humidity sensing, provide a smart material for artificial skin applications. The smart material consists of humidity and temperature responsive p-NIPAAm hydrogel core with defined Lower Critical Solution Temperature (LCST). The outer shell is build up by piezoelectric ZnO. The piezoelectric response of the Zinc Oxide shell is created from either external applied pressure and/or swelling of the inner hydrogel core. The hydrogel swells upon changes in humidity or temperature in the environment. Based on the work of Muralter et al., p-NIPAAM with different LCST is obtainable by Initiated Chemical Vapor Deposition (iCVD). The process allows solvent-free preparation and deposition of highly uniform and conformal organic polymers. Additionally, iCVD allows cross linked polymerization of NIPAAm to obtain different swelling % and LCST [1]. Piezoelectricity in Zinc Oxide is dependent on the preferential orientation of the film grown. The work of Pilz et al. demonstrates the usage of Plasma Enhanced Atomic Layer Deposition (PE-ALD) to obtain thin Zinc Oxide films with controlled preferential orientation. For substrate temperatures below 100 °C, (100) preferential orientation has been obtained whereas the preferential orientation switches to (002) for temperature above 100 °C [2]. Preparation of nanorods is done by patterning a template material, where nanotrenches are patterned using Ultraviolet-Nanoimprint Lithography (UV-NIL) or Thermal-Nanoimprint Lithography (T-NIL). The nanopatterning step is followed by deposition of a Zinc Oxide layer followed by a hydrogel layer to fill the trenches. In the course of the nanopatterning process, different template materials will be investigated regarding their elastomeric properties. Investigated materials include PMMA, PUA and PDMS. Moreover, the influence of the nanorod aspect ratio, Zinc Oxide layer thickness and template material on the swelling of the hydrogel core and the nanorod output piezoelectric potential is investigated using COMSOL Multiphysics.

Resume : Carbon nanomaterials such as carbon nanotubes (CNTs) and graphene have revealed peculiar electrical [1], thermal [2] and mechanical [3] properties, but one of the most serious constraints, which limits their application, is their lack of compatibility with other materials such as polymers. The reason for this is their apparent hydrophobic character, which is alleviated by chemical modification, which equips the surface with the necessary characteristics to make it easily wettable by water-like molecules. Our recent results, based on CNT networks produced in house [4], have shown that it is not unlikely that the character of the surface is hydrophilic by default and what we observe is just an illusion [5,6] caused by contamination present on the surface. In this contribution, we would like to present interpretation of this phenomenon and delineate the most probable upcoming applications of this effect. References: [1] A. Lekawa-Raus, T. Gizewski, J. Patmore, L. Kurzepa, K. Koziol, Electrical transport in carbon nanotube fibres, Scripta Materialia 131, 2017, 112–118. [2] K. Koziol, D. Janas, E. Brown, L. Hao, Thermal properties of continuously spun carbon nanotube fibres, Physica E: Low dimensional Systems and Nanostructures 88, 2017, 104-108. [3] M.-F. Yu, O. Lourie, M. J. Dyer K. Moloni, T. F. Kelly, R. S. Ruoff, Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load, Science 287, 2000, 637-640. [4] D. Janas, M. Rdest, K. Koziol, Free-standing films from chirality-controlled carbon nanotubes, Materials & Design 121, 2017, 119-125. [5] D. Janas, G. Stando, Unexpectedly strong hydrophilic character of free-standing thin films from carbon nanotubes, Scientific Reports 7, 2017, 12274. [6] D. Janas, G. Stando, D. Lukawski, F. Lisiecki, Intrinsic hydrophilic character of carbon nanotube networks, Applied Surface Science 463, 2019, 227-233.

Resume : Development of a spectrum of nanostructures has revealed a range of potential applications that they may have. For instance, depending on the way they are ordered at the nanoscale, their electrical properties can range from superconducting (YBCO), metallic (Ni, Pt, Au), semiconducting (Si) to isolating (SiO2, TiO2). Careful design of these interesting architectures enables one to tailor the properties of the material, so that it matches the expected field and type of exploitation. In particular, Nickel Nanowires (NiNWs) are very interesting due to the fact that they can be created from inexpensive precursors [1,2], but they offer promising characteristics. In this contribution we present how they can be produced using a simple reduction of Ni ions in liquid medium [3] and used as a catalyst [4] in model chemical reactions. Because of the possibility to make thin films from this material we believe that they could be very useful for heterogeneous catalysis. References: [1] P. Liu, Z. Li, Template-free synthesis of nickel nanowires by magnetic field, Materials Letters 63, 2009, 1650. [2] Z. Xia, W. Wen, Synthesis of Nickel Nanowires with Tunable Characteristics, Nanomaterials, 2016, 6, 19. [3] T. Wasiak, L. Przypis, K. Walczak, D. Janas, Nickel Nanowires: Synthesis, Characterization and Application as Effective Catalysts for the Reduction of Nitroarenes, Catalysts, 2018, 8, 566. [4] T. Siudyga, M. Kapkowski, D. Janas, T. Wasiak, R. Sitko, M. Zubko, J. Szade, K. Balin, J. Klimontko, J. Polanski, Oxide passivated nano-Ru supported on Ni nanowires for low-temperature carbon dioxide methanation, ChemCatChem (submitted)

Resume : Nanocomposite Mo-Si-B and Mo-Hf-Si-B coatings were deposited by direct current (DCMS) and pulsed magnetron sputtering (PMS) of the MoSiB and MoHfSiB composite targets fabricated by the self-propagating high-temperature synthesis method. The structure, element and phase composition of coatings were studied by means of scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, Raman, and glow discharge optical emission spectroscopy. The films were characterised in terms of their adhesion, hardness, elastic modulus, elastic recovery, fatigue strength, and fracture toughness. To evaluate oxidation resistance, the coatings were annealed in air in the temperature range of 600-1500°C during different time expositions between 10 min and 5 h. The results obtained demonstrate that the Mo-Si-B coatings possess higher hardness of 30 GPa, improved oxidation resistance and better thermal stability compared with their Mo-Hf-Si-B counterparts. The 14 microns thick Mo-Si-B coatings were shown to withstand successfully oxidation during short-time exposure for 10 min at temperature as high as 1500°C due to the formation of protective silica scale. The oxidation of Mo-Hf-Si-B coatings was accompanied by the diffusion of hafnium to the coating surfaces and the formation of SiO2/HfO2/SiO2 top-layer structure which were less protective against oxidation. Formation of Al2O3-SiO2 and HfO2 layers on the boundary with the substrate was also revealed in case of Mo-Hf-Si-B films. Other hand doping with hafnium exclude the complete destruction of MoSiB coatings after annealing at 600°C due to silicide pest effect. The work was supported by the Russian Science Foundation (Agreement No. 19-19-00117).

Resume : C-N coatings were deposited by RF sputtering method from a pure Cr target on XC100 steel substrates in a mixture of N2 and Ar gases. In order to examine the formation of chromium nitrides, carbides and carbonitrides phases, and the coatings were subjected to annealing treatment between 900 to 1000 °C. The samples were characterized by EDS, XRD, SEM, nanoindentation and tribometer. The results showed the appearance of Cr2N and CrN during at 800°C and the emergence of chromium carbonitride phases only at 900 °C. The (111) fcc CrN phase was changed to (002) that appeared in parallel with the chromium carbides. Nanoindentation test revealed a regular augment of theelastic modulus from 204 to 264 GPa with increasing the annealing temperature from 800 to 900°C, while the hardness showed a maximum value (H=22 GPa) at 900°C. The best friction coefficient of the Cr-C-N coating was approximately 0.42 at 900°C. The improvement of mechanical and tribological properties was ascribed to the formation of Cr-C binding energy at the CrN/XC100.

Resume : Ion implantation is one of the most universal methods of surface modification of the solid materials. Implantation of heavy ions, such as Au-, allows obtaining high density of cascades and creation regions of disordering in the irradiated solid due to various interactions between implanted ions and atoms of the solid with subsequent irradiation stimulated diffusion. From the other side, multilayer coatings, consisting of alternating nanoscale layers, made of two or three types of materials with different structure and properties, allow fabrication of coatings with high hardness up to 40 – 50 GPa. It is known, that epitaxial structure can be formed in such coatings and superhardness effect can be found for specified modulation period. High-dose ion implantation (up to 2x1017 ions/cm2) of such multilayer coatings can lead to ion mixing on the layers borders, as well as on interfaces. Various methods of analysis, such as HRTEM, STEM, XPS, SIMS, XRD and EDS with microanalysis were used for coatings characterization, both in the as-deposited and implanted state. Complex studies of defect structure, redistribution of elements and changes of microstructure of the (TiAlSiY)N/CrN multilayer coatings are presented.

Resume : In order to develop advanced hemodiafiltration membrane with favorable biocompatibility and efficient dialysis performance, novel thin film nanofibrous composite (TFNC) ultrafiltration (UF) membranes consisting of sulfonated poly(vinyl alcohol) (s-PVA) blended PVA hydrogel barrier layer and electrospun polyacrlonitrile (PAN) nanofibrous supporting layer were designed and fabricated by combining electrospinning and conventional surface coating techniques. The mesh sizes of hydrogel network of s-PVA/PVA barrier layer could be tuned by varying the blending content of s-PVA. The optimized s-PVA/PVA TFNC UF membrane (S-P-TFNC-1-3) possessed high pure water flux up to 380 Lm-2h-1bar-1 with high bovine serum albumin (BSA) rejection (> 90%). Besides, the introduction of s-PVA into the hydrogel barrier layer endowed the TFNC membranes with enhanced hydrophilicity, antifouling property and biocompatibility (decreased protein adsorption, prolonged clotting time, suppressed platelet adhesion, lower hemolysis ratio and more benefits for cell proliferation) due to the presence of sulfonic groups. The dialysis simulation experiment results of S-P-TFNC-1-3 showed that 84.2% of urea and 60.9% of lysozyme were cleaned and over 95% of BSA was retained after 4h dialysis process. Especially, the removal of middle-molecule uremic toxin was more efficient than conventional hemodialysis membranes reported so far, and high retention of big proteins was achieved simultaneously. This work exposes a window of opportunity for modified PVA TFNC membranes in blood purification applications.

Resume : Metal organic frameworks (MOFs) are emerging as a novel class of high-effective and promising adsorbents for pollutants sequestration due to their high porosity and rich functionalities. However, their intrinsic fragility and poor separability limited their practical applications. Herein, an intriguing MOF UiO-66-(COOH)2 nanoparticles with abundant carboxyl functional groups were encapsulated into polyacrylonitrile (PAN) nanofibers by colloid-electrospinning technique to construct flexible MOF nanofibrous membranes (NFMs) with hierarchical structure for effective recovery of lanthanide (Ln) ions and sustainable reutilization in photoluminescent applications. The MOF UiO-66-(COOH)2 contained twenty-four free carboxyl functional groups per crystal which could endow it with powerful affinity to Ln3+ ions. The resultant PAN/UiO-66-(COOH)2 NFMs with quite high UiO-66-(COOH)2 loading (up to 60wt%) exhibited outstanding adsorption capacities and good recyclability for Ln3+ ions. The adsorption data could be better fitted by the Langmuir isotherm and pseudo-second-order kinetic models, and the maximum adsorption capacities of Terbium(III) (Tb3+ ) and Europium(III) (Eu3+ ) ions calculated from the Langmuir isotherm model were 214.1 mg/g and 191.9 mg/g, respectively. Moreover, it was found that the adsorbent could be well regenerated without obvious loss of adsorption capacities after three adsorption-desorption cycles. In addition, benefiting from the carboxyl ligands acting as excellent sensitizers for Tb3+ and Eu3+ ions, the Ln3+-loaded PAN/UiO-66-(COOH)2-60 NFMs showed a series of characteristics including good photoluminescence properties, tunable emission colors and robust softness, indicating their use as promising luminescent materials for luminescent patterning and optoelectronics.

Resume : Supramolecular polymers show unique and excellent properties due to the reversible and designable nature of the non-covalent interactions. Herein, ureido-pyrimidinone (UPy)-based supramolecular polymers were employed to fabricate the thermo-responsive composite materials with multi-walled carbon nanotubes (MWCNTs) by planting the MWCNTs onto the supramolecular polymer matrices via a simple surface spraying procedure. The MWCNTs coating on the surface of the supramolecular polymer matrices gave the composite film superhydrophobic and conductive properties, and it had a non-contact healable ability underwater under 808 nm near-infrared light (NIR) irradiation. Moreover, the UPy-based supramolecular polymers acted as thermo-responsive matrices to guarantee the self-healing properties at a relatively low temperature, such as body temperature (33 °C–34 °C). The supramolecular polymer/ MWCNTs composite materials exhibited excellent strain sensitivities and could be used to prepare human motion-monitoring devices. Meanwhile, non-contact IR or body temperature self-healing property will greatly extend the life of the device. It provides a promising possibility for the development of the next generation of health monitoring system applied in underwater environments. This line of research may find a promising practical application in healable wearable devices used in particular conditions. And we hope this scheme can provide a new avenue for the design and preparation of functional devices with supramolecular polymeric materials. (This paper is funded by the International Exchange Program of Harbin Engineering University for Innovation-oriented Talents Cultivation.)

Resume : Developing a cost-efficient and environmental friendly separation membrane for the desalination of hypersaline water is significant but challenging because of the crucial limitations of low permeate flux and serious membrane pore wetting over time. Herein, a unique dual-layer composite membrane consisting of a superhydrophobic selective skin from amorphous polypropylene (aPP) and an electrospun poly(vinylidene fluoride) (PVDF) nanofibrous support was created via a facile vacuum filtration method. Benefitting from the excellent tackiness and low surface energy of aPP, the robust dual-layer aPP/PVDF membranes not only could exhibit remarkable enhancement in hydrophobicity and liquid entry pressure of water (LEPw) but also could tune the pore size without severe compromising the porosity. The superhydrophobic aPP porous skin acted as additional barrier to surface wetting and combined the interconnected nanofibrous support to provide direct paths for vapor transport, leading to superior direct contact membrane distillation (DCMD) performance. Significantly, the optimal superhydrophobic aPP/PVDF membrane exhibited a ultrahigh permeate vapor flux of 53.1 kg/(m2•h) and stable permeate conductivity for transmembrane temperature of 40 °C (3.5 wt% NaCl salt feed) over 50 h operation. This DCMD performance was more than twice that of typical commercial PVDF (C-PVDF) membrane and even better than those of modified electrospun nanofibrous membranes (ENMs) reported so far, indicating great applicability for MD desalination.

Resume : There have been significant interests about radiative cooling of the solar cell device in order to increase the efficiency of the solar cell. Under solar irradiation, the significant amount of absorbed solar energy are not converted into the electricity, generates heat and raises the operating temperature of the solar cell. The operating temperature of the solar cell is reported to be 50 °C ~ 55 °C or higher under the outdoor sun lighting ambient. Under this high operating temperature condition, reliability and efficiency of the solar cell would deteriorate significantly. Therefore, various techniques for solar cell cooling have been developed: conduction of heat into the dissipative surface, convection of airflow, water flowing, including radiant cooling. More recently, the silica pyramidal array on top of the solar cell is reported to lower the solar cell temperature by 15 °C [1, 2]. In this report, the silica pyramid on the centre of the pyramidal pit has been microfabricated for both light trapping and radiative cooling. The fabricated plasmonic pyramidal pit array can provide the enhanced light intensity and photon absorption from trapping in the pyramidal groove, in addition, self-cooling can be achieved from the fabricated silica volcano surrounded with the silicon solar cell in the far infrared wavelength range of (8 ?m ~ 13 ?m) via radiative cooling. Reference [1] S. Fan et al, ?Radiation cooling by solar cells,? Optical vol 1, 32(2014) [2] S. Fan et al, ?Passive radiative cooling below ambient air temperature under direct sunlight,? Nature, vol 515, 540(2014).

Resume : The problem of efficiently obtaining of hydrogen through photoelectrochemical water splitting is one of the most promising areas of renewable energy. Titanium dioxide with photocatalytic activity in the ultraviolet region is one of the most common photoanode materials for this process, its only drawback is the lack of activity in the visible range of solar radiation. Currently, an intensive search of new photoelectrode material for this process is conducted. A polymer-like semiconductor, carbon nitride g-C3N4, are discerned to be promising as photoelectrode material for producing hydrogen by water splitting under visible light irradiations with wavelength below 460 nm. However, for doped by oxygen g-C3N4 (O-g-C3N4) photoactivity boundary in the visible spectrum expands to 498 nm. Consequently, O-doped g-C3N4 films would absorb more visible light than pristine g-C3N4 films. In this work, we introduce a facile procedure to obtaining of O-doped g-C3N4 film on Ti surface by one-step CVD approach using urea as precursor under air atmosphere. Titanium foil with a thickness of 0.5 mm and an area of about 0.5 cm2 was used as a substrate. Deposition O-g-C3N4 film on Ti surface has been confirmed by SEM, XRD, XPS and FTIR spectroscopy. According to the XPS results O-g-C3N4 film contains 6% oxygen. The facile deposition method can be promising for the fabrication of efficient and low-cost photoelectrodes based on O-doped g-C3N4 films for photoelectrochemical water splitting.

Resume : In this work, we investigate the influence of different types of thermal annealing on structural, optical and electrical properties of Copper iron oxide thin films. The films were co-sputtered from metallic copper Cu and iron Fe targets in the presence of a reactive argon and oxygen gas mixture, and then annealed under vacuum and air atmosphere at different temperatures (380, 450 and 550°C). The X-ray diffraction XRD shows that the as-deposited thin films were initially amorphous. CuFe2O4 and CuO as the secondary phases were clearly detected by XRD analysis of the air-annealed films. While, for the films annealed under vacuum, we have found that the polycrystalline CuFeO2 thin film was obtained at 450°C. Optical studies reveal that the air-annealed films show a direct optical band gap increase from 2.05 to 2.9 eV as function of annealing temperature. Furthermore, the samples annealed under vacuum have relatively high transmission up to 90% and reveal a two direct band gap in the range 1.65-2.14 eV. Relatively, the annealing treatment such as under vacuum improves the physico-chemical properties of the samples. Keywords: Copper iron oxide, thin films, reactive magnetron sputtring, annealing, opto-electronic properties.

Resume : The effect of polyethylenimine(PEI)-treated multi-walled carbon nanotubes(MWCNT) coating on the carbon fiber surface topography and the interfacial properties of carbon fiber/polymer composites was studied. MWCNT nanoparticles treated with PEI, which is a cationic polymer with amine groups, were coated on the carbon fiber surfaces by using electrolytic solution. Carbon fiber/acrylonitrile-butadiene-styrene(ABS) and carbon fiber/epoxy composites with four different fiber coating cases were prepared for single fiber microbonding tests, respectively. The composite with pristine carbon fiber showed the lowest interfacial bonding between the fiber and the matrix due to the plain carbon fiber surface. When carbon fiber was coated with the MWCNT only, the coating was not successful because there was no chemical interaction between the MWCNT and the carbon fiber. When carbon fibers were coated with the MWCNT treated with relatively high molecular weight PEI, the surfaces were partially coated and the MWCNT were not well distributed to the fiber surfaces with some aggregations. When carbon fibers were coated with the MWCNT treated with relatively low molecular weight PEI, the aggregation of PEI and MWCNT was hardly found and the MWCNT were uniformly distributed on the fiber surfaces forming a network structure, resulting in the highest interfacial shear strength (IFSS) among the four coating cases. Carbon fiber/epoxy composite showed higher IFSS than carbon fiber/ABS composite.

Resume : Thanks to their small sensing volume, nanosensors based on localized surface plas- mon resonances (LSPR) allow the detection of minute amounts of analytes, down to the single molecule limit. However, the detected analytes are often large molecules, such as proteins. The detection of small molecules remains largely unexplored. Here, we use a hybrid photonic-plasmonic nanosensor to detect a small target molecule (pyri- dine). The sensor’s design is based on a dielectric photonic microstructure acting as an antenna, which efficiently funnels light towards a plasmonic transducer and enhance the detection efficiency. This sensor exhibits a limit of detection as small as 10−14 mol.L−1. Using a calibration procedure based on electrodynamical numerical simula- tions, we compute the number of detected molecules. This yields a limit of detection in mass of 4 zeptograms (1 zg = 10−21 g), a record value for plasmonic molecular sensors. Our system can hence be seen as an optical molecular weighing scale, enabling room temperature detection of mass at the zeptogram scale.

Resume : Platinum displays outstanding performance for the electrocatalysis of small organic molecules such as glycerol1. The important issue concerns the decrease of the amount of Pt in electrodes. This can be achieved by using bimetallic catalysts based on Pt nanoclusters. Pt-Cu or Pt-Bi nanoclusters can help to decrease the amount of Pt while maintaining the catalytic activity of the electrodes. Magnetron sputtering coupled to a Gas Aggregation Source (GAS) is used because it allows obtaining clusters with an optimum size control of a broad variety of materials providing a continuous nanocluster beam2,3. In this work, metallic Pt, Pt-Bi and Pt-Cu nanoclusters were grown using GAS. Variation of the composition of bimetallic clusters was achieved by setting different electrical parameters for co-sputtering. The size, nanostructure and morphology were obtained by in-situ quadrupole mass spectrometry, grazing incident X-ray diffraction and HRTEM measurements. The catalytic activity of the Pt-based electrodes was evaluated in presence of glycerol by using electrochemical measurements. The aim of this work is to give an insight about the relationship between composition, nanostructure and catalytic activity of the Pt-based nanocluster electrodes and their influence during the electrooxidation of glycerol. (1) Simões, M.; Baranton, S.; Coutanceau, C. Electrochemical Valorisation of Glycerol. ChemSusChem 2012, 5 (11), 2106–2124. (2) Haberland, H.; Karrais, M.; Mall, M.; Thurner, Y. Thin Films from Energetic Cluster Impact: A Feasibility Study. J. Vac. Sci. Technol. Vac. Surf. Films 1992, 10 (5), 3266–3271. (3) Caillard, A.; Cuynet, S.; Lecas, T.; Andreazza, P.; Mikikian, M.; Thomann, A.-L.; Brault, P. PdPt Catalyst Synthesized Using a Gas Aggregation Source and Magnetron Sputtering for Fuel Cell Electrodes. J. Phys. Appl. Phys. 2015, 48 (47), 475302.

Resume : Broadband photodetection, from UV to SWIR, is required in a large range of applications, such as optical metrology, bio-chemical sensing. food quality monitoring, survelliance systems, colorimetric and multispectral imaging. This work presents the structure, fabrication process and characterization of thin film photodetectors for a broad spectral range, from UV to SWIR. A first layer of ZnO nanowires (NWs) grown on a glass substrate with ITO electrodes have been used to obtain a good response in UV. The NWs were coverd with a PbS based hybrid nanocomposite. Large PbS QDs with first excitonic absorption peak ~1400 nm have been used To extend the spectral range in SWIR. The PbS QDs solution was mixed with a P3HT:PCBM polymer blend to improve the absorption in the green range, to facilitate ambipolar transport and the charge extraction from the PbS QDs. The entire fabrication process, including ZnO NW grow, spin and drop casting of the nanocomoosite, electrode deposition were carried out at temperatures below 200°C. This ensures compatibility to other thin fil devices and even with Si circuits. The photodetector spectral characteristics exhibits 3 major peak (~ 0.4A/W) in UV, vis (550 nm) and SWIR (1450 nm) range. , and an additional peak in near IR (1100 nm). The peak responsivities were further increased, up to 1A/W at 370 nm and 0.6- 0.& A/W in vis and SWIR ranges by adding plasmonic nanoparticles in the nanocomposite. The plasmonic nanostructures improve the photocurrent generation by light trapping and/or electromagnetic field local enhancement due to the excitation of localized surface plasmons (SPPs). The obtained characteristics offer prospects use the device in multi-chanel detection over a broad spectral range, from UV to SWIR.

Resume : Plastic organic LEDs (P-OLEDs) are being used widely because of their thinness, shape flexibility, and low pixilation. However, P-OLEDs exhibit low light extraction efficiency (LEE) due to coupling of emission to guided photonic and plasmonic modes. Additionally, blue phosphorescent P-OLED emitters are unstable due to long emission lifetimes, excited-state quenching, and large band gap. This study theoretically and experimentally investigates the use of Ag plasmonic metasurface structures to increase the light extraction efficiency, radiative decay rate and stability of inverted P-OLED devices. Electromagnetic simulations are used to design Ag metasurfaces and to quantify the extent to which they increase LEE and radiative decay rate of OLED emissive layers. Both one- and two-dimensional Ag gratings are investigated with different grating periods, aspect ratios and etching depths. The simulation results show that the optimized metasurface improves the LEE by 80% for 465 nm wavelength light emission. Ag metasurface back electrodes are fabricated by nanoimprint lithography and integrated into Ir(ppy)3:PVK P-OLEDs. MoO3 is used as the hole transport layer on the metasurface and ZnO-Ag-ZnO is used as the top electrode. Luminance and chromaticity tests are carried out to determine the effects of the Ag metasurface on LEE, emission rate and stability, and the experimental results are compared to the theoretical simulations to further validate our approach.

Resume : Plasmons, the surface plasmon resonance and localized-surface plasmon resonance, had been investigated from the perspectives of the fundamental science. Recently, plasmons have been attracted intense attentions for their applications to multifunctional devices owing to their infinite potentials. “Hot spots” are homogeneous and enhanced electric field in the vicinity of noble metals induced by a “coupling” between plasmons. At the hot spots, the interaction between the physical properties of materials and incident light could be possible to create novel functionalities of the materials. In this study, we investigated the interplay of nanostructural magnetic material and hot spots. Namely, we attempted an enhancement of magneto-optical (MO) effect, i.e., MO Kerr rotations, of nanomagnets with the assistance of the hot spots. The sample structure in our study is composed of terbium-iron cobalt thin film and self-organized gold nanoparticles. The terbium-iron cobalt is a magnetic material exhibiting MO Kerr rotations. On the other hand, the self-organized gold nanoparticles were used to generate hot spots. The MO Kerr rotation angles of the samples were largely influenced by the structures of the samples and thickness of terbium-iron cobalt thin film. The MO Kerr rotation angles were markedly different between terbium-iron cobalt thin film and terbium-iron cobalt nanomagnets. The outstanding enhancement of MO Kerr rotation angles was achieved; we obtained two times higher MO Kerr rotation angles than those of terbium-iron cobalt thin film. This result implies the effectiveness of the interplay of nanostructuring and hot spots. Throughout the present study, we found the possibilities of manipulation of physical properties with the assistance of nanostructuring and hot spots.

Resume : Nanocomposite coatings containing metal nanoparticles have received increasing interest from both researchers and industry in the last decades. One of the main properties of interest of the metal nanoparticles is their ability to support Localized Surface Plasmon Resonances (LSPRs), optically induced oscillations of free electrons at the surface of the metal nanoparticles. The excitation of LSPRs by incoming light results in strong light extinction effects that are heavily dependent on the nanoparticle’s dielectric constant, size, shape and concentration and also on the dielectric constant of the surrounding medium. Each coating application requires a specific LSPR signal and therefore it is mandatory to deposit nanocomposites with great control over the nanoparticle’s morphology and its distribution in the matrix. In this work, Au nanoparticles were incorporated into different matrixes (Al2O3, WO3, TiO2 and AlN) using three different sputtering techniques: (i) co-sputtering followed by thermal annealing treatments; (ii) alternating-sputtering using pulsed DC power sources and (iii) alternating-sputtering using a plasma gas condensation (PGC) nanoparticle source. The design of the coatings was carefully optimized according to the application in view (hard decorative coatings or gas sensors). The first method allowed the deposition of nanocomposites with a relatively homogeneous dispersion of spherical Au nanoparticles within the matrixes (with sizes up to 8 nm). The second method allowed a more effective and independent control over the nanoparticles morphologies without the need of thermal annealing treatments (spherical and spheroidal nanoparticles with sizes up to 15 nm were incorporated in the matrixes). The third method allowed the production of large amounts of nanoparticles with high level of control over its mean size (spherical nanoparticles with sizes between 5-65 nm were deposited with varying deposition rates and size dispersions). The functional properties were studied and related with the structure and microstructure of the coatings.

Resume : Metallic oxide nanostructures are promising materials in photocatalysis applications, for example in water treatment and disinfection or for hydrogen production by water splitting. Growing metallic oxide nanostructures can be achieved by simple thermal oxidation of raw metallic materials. The use of afterglow plasma treatments improve the control of the design of nanostructures by moving the temperature window where nanostructures are formed by about 100 K downward. This shift enables the development of higher stress levels and offers the possibility to create dense areas of nanostructures. For a given nanostructure, it is even possible to design them by driving growth instabilities using mixtures of metals. We can thus expect to control the growth of ultrathin nanowires. For instance, the synthesis of ultrathin, single-crystalline zinc oxide nanowires was achieved by treating in a flowing microwave plasma oxidation process, zinc films coated beforehand by a sputtered thin buffer layer of copper [1]. An average diameter of 5 nm correlated with a mean length of 750 nm can be reached with a fairly high surface number density for very short treatments, typically less than 1 minute. An enhancement of photocatalytic activity and photocurrent intensity under visible and UV light is observed for ultrathin nanowires, attributed to low recombination of photoinduced electron-hole pairs. References [1] A. Altaweel et al., Nanotechnology 28 (2017) 085602.

Resume : Nanoporous metallic networks are 3D solid structures with an overall macroscale size, which are built of nano-size ligaments and pores. These networked-metals, also abbreviated as ‘Netals’, are a rather new class of materials having promising applications owing to their huge surface area, their strong interaction with light, and the possibility for unique combination with exciting chemical moieties. Therefore, they attract a great focus as advanced materials for catalysis, photonics, sensing, and renewable energy. Normally, physical vapor deposition (PVD) is used to form fine homogeneous thin-films. However, herein we present that 3D nanoporous metallic networks can directly grow by means of PVD on a mesoporous and electrostatic silica substrate. The innovative aspect of this technique is that the fused building-block nanoparticles are not pre-synthesized, but rather formed during the deposition process, and therefore the resulted metallic network is pure- a property which greatly dictates their optical and catalytic performances. Such metallic networks, that can be prepared from various types of metals, can be employed as large-scale photocatalysts due to generation of energetic carriers which can promote chemical reactions. As well, the strong electromagnetic field emanating from the network surface and the probability of generating hot-electrons support an enhanced surface-enhanced Raman scattering (SERS). The suboptical wavelength sizes of both particles and voids provide the networks with interesting optical properties. For example, these Netals introduce distinct colors which are different from the corresponding bulk metals, and are attributed to surface plasmon excitations. The plasmonic behavior of 3D nanoporous silver networks was resolved by means cathodoluminescence (CL) measurements showing a multimode nature not only from different locations at the network, but also from along a single ligament. In addition, silver networks introduce a broad nonlinear optical response coming into expression as intense second harmonic generation (SHG) emission. The mechanism that governs the growth of these networks is not fully deciphered yet, however the effect of key parameters such as substrate morphology, surface chemistry, surface charge, and PVD conditions will be introduced. 1. R. Ron, E. Haleva, A. Salomon. Advanced Materials, 2018, 30 (41), 1706755. 2. R. Ron, D. Gachet, K. Rechav, A. Salomon. Advanced Materials, 2017, 29 (7), 1604018.

Resume : Nanoplasmonic thin films composed by noble nanoparticles embedded in an oxide matrix have been a subject of considerable interest for optical sensing, due to their localized surface plasmon resonance (LSPR) properties. In the present work, nanoplasmonic thin films were deposited by reactive DC magnetron sputtering and then submitted to annealing treatments to promote the growth and coalescence of the Au and/or Ag nanoparticles inside a dielectric (or semiconductor) matrix. In order to tune the optical response of the thin films they were prepared with different amounts of Au and/or Ag embedded in different host matrixes, such as TiO2, CuO, Al2O3 and AlN. The aim is to develop nanoplasmonic platforms capable of sensing molecular analytes (either gas molecules or biomolecules) through changes perceivable in the LSPR band (shifts in LSPR peak and transmittance values, band width or integral area). The composition, microstructure and optical response of the thin films were studied as a function of the metal concentration and annealing temperature and correlated with the LSPR behaviour. LSPR bands were clearly observed in the different systems prepared, and their position and curvature depended on the concentration of the metallic nanoparticles (Au, Ag and Au-Ag), on the different sizes distributions induced by the annealing treatment and of the host matrix. The sensitivity to different dielectric environments (either gas molecules or liquid solutions) was also evaluated and correlated with the nanostructure of the films.

Resume : Direct bandgap crystalline GeSn, as ecologic and compatible with silicon technology material has great prospects in optoelectronics, especially for shortwave infrared (SWIR) range. But its easy fabrication still remains challenging. Embedding GeSn nanocrystals in an amorphous matrix hinders the formation of grain boundaries defects, such as the light sensing is enhanced. In this work we present the fabrication of Short Wave InfraRed (SWIR) photosensitive layers based on GeSn nanocrystals, by using the magnetron sputtering deposition of (Ge1-xSnx)y(SiO2)1-y alloys. GeSn nanocrystals embedded in the SiO2 amorphous matrix were formed either by post-deposition annealing (350 to 450oC), or during deposition (300 to 370oC). The Sn and SiO2 concentrations were varied in the ranges 12 to 22 at.% and 11 to 15 at.%, respectively. The small quantity of Hydrogen (5%) added to Ar enhanced the nanocrystallization and increased the photosensitivity. The morphology, composition and structure of layers were investigated by HR-TEM, XRD and XPS. Spectral photovoltaic current measured on heterojunctions of GeSn-NCs with p-Si substrate showed extended SWIR sensitivity up to 2.4 µm in samples containing nanocrystals of 15 at.% Sn. We acknowledge the support of UEFISCDI, contract no.58/2016 - project M-ERA.NET GESNAPHOTO and contract no. 39/2018 - project GETINEPFE, as well as the Romanian Ministry of Research and Innovation: 2019 Core Programs of NIMP and INOE.

Resume : Transition metal nitrides possess high thermal stability, high hardness, good tribological properties. Among them, some nitrides, such as zirconium nitride, excel in their optical and electrical properties, making them a suitable material for plasmonic applications. In this work, we deal with a study of the growth process of zirconium nitride (ZrNx) films by means of RF magnetron sputtering of Ti target in a reactive nitrogen ambient. The resulting structure and corresponding plasmonic properties of ZrNx coatings are very sensitive to some deposition parameters, especially, the composition of Ar/N2 gas mixture. Different chemical compositions, such as ZrN, Zr2N, Zr3N4, and ZrN2, can be obtained via the control of the sputtering reactive gas mixture that leads to different physical properties of the resulting zirconium nitride film. The films are grown on fused silica, silicon and MgO substrates at a substrate temperature ranging from 20°C to 500°C. The growth process is monitored using an in-situ spectral ellipsometer in a spectral range from 245 to 1690 nm. The ellipsometric data are analyzed using mathematical models based on Drude-Lorentz oscillators. A number of physical parameters, such as free-electron concentration, Drude relaxation time and electrical resistivity, are estimated at each stage of the deposition process by proper analysis of dielectric functions. Special attention is paid to the initial stage of growth when the free-electron behavior is significantly influenced by the interface between the substrate and the ZrNx film. The obtained results are compared and discussed with those obtained by Van der Pauw and Hall effect measurement. The crystallinity and surface morphology were analyzed by X-ray Diffraction method (XRD) and Atomic Force Microscopy (AFM).

Resume : Noble metal nanoparticles have been deeply investigated due to their unique optical properties related to the Localized Surface Plasmon Resonance (LSPR) phenomenon. The nanoparticles’ optical response can be tailored by changing their morphological and geometric characteristics (size, shape and distribution) and dielectric function of the surrounding host matrix. When these nanoparticles are embedded in a porous host matrix, e.g. produced using a GLancing Angle Deposition (GLAD) system, analyte molecules can easily diffuse to the vicinity of the nanoparticles and induce subtle changes in the refractive index. These interactions can be detected in transmittance spectra by monitoring the shape of the LSPR extinction band (T-LSPR). Therefore, several transduction mechanisms can be used to build T-LSPR sensors. This work combines (i) the preparation of nanostructured plasmonic thin films, (ii) sensitivity studies and (iii) LSPR extinction band processing. An environmentally friendly physical deposition method (reactive magnetron sputtering), with a GLAD system was used, allowing the preparation of plasmonic thin films with tailored porosity. Refractive index sensitivity studies were conducted in a controlled atmosphere chamber with real-time T-LSPR monitoring. The obtained signals were then processed using an algorithm that analyses changes in several parameters of the LSPR extinction band. The results showed that the refractive index sensitivity of the films is improved for higher porosities, thus confirming the possibility of using these nanostructured plasmonic thin films as T-LSPR sensors.