Organized nanostructures and nano-objects: fabrication, characterization and applications

Resume : [Ge-TaZrOx/TaZrOx] superlattices were fabricated by confocal radio-frequency magnetron sputtering. After annealing the superlattices, spherically shaped Ge nanocrystals with well controlled size and spatial distribution have been formed as confirmed by transmission electron microscopy. Raman scattering showed that the crystallization of the Ge starts at 700 °C. In contrast, the TaZrOx matrix crystalizes at 770 °C via the formation of orthorhombic zirconium oxide and orthorhombic tantalum oxide as confirmed by X-ray diffraction. Thus, the material system allows the controlled formation of Ge nanocrystals in an amorphous ZrO2-based high-k matrix material. The size and size distribution of the nanocrystals depends strongly on the Ge-TaZrOx composite layer thickness. The size of the nanocrystals formed from 3 nm and 6 nm thick composite layers corresponds to the layer thickness. Composite layers of 9 nm and 12 nm thickness form two fractions of nanocrystals with different sizes. The size control is thus less suitable for composite layers larger than 6 nm. An additional SiO2 layer underneath the composite layer leads to the formation of larger and better separated Ge nanocrystals. The influence of the matrix material on the formation of the nanocrystals is discussed in detail.

Resume : Room temperature (RT) operation of Single Electron Transistors (SETs) is based on two conditions: (i) The Coulomb blockade energy of charging a dot must be smaller than kT, i.e. a Si quantum dot must be <5nm. (ii) The electron tunneling distance from the Si dot embedded in SiO2 to an electrode must be <1.5nm. Such dimensions are beyond the limits of top-down processes like Electron Beam Lithography (EBL) and Reactive Ion Etching (RIE). As we demonstrate by atomistic computer simulations, a functional nanostructure for RT-SETs can be achieved by bottom-up processes, i.e. self-organization and self-alignment: Phase separation in a tiny volume ~(10nm)3 of metastable SiOx results in the formation of a single Si precipitate in SiO2 . And, if this SiOx volume is bordered at two sides by a Si/SiOx interface, the Si dot becomes self-aligned (isolated) by a SiO2 layer (SiOx denuted by excess Si). The tiny SiOx volume has been formed by top-down processes: From a bulk Si/7nm SiO2/a-Si layer stack nanopillars of <20nm diameter have been fabricated by EBL and RIE. Then, the SiO2 layer embedded in the nanopillar was transformed into SiOx by 50keV Si ion irradiation. During subsequent annealing the single Si dot is expected to form. Two nanoscale phenomena not observed so far have to be overcome to get a reliable RT-SET fabrication. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 688072.

Resume : This talk will present the method of self-aligning gas phase electrodeposition and will address applications such as nano interconnects, vias or gas sensors. Recently, new trends have emerged in the area of interconnects and vias for semiconductor components. The semiconductor industry is now looking for ways to integrate new non-copper-based materials such as ruthenium or new self-aligned technologies into existing production processes. In contrary to conventional metallization, ruthenium has a better conductivity in the nano range than copper or aluminium. Another interesting feature is the possibility of electrically connecting arbitrary points on the chip. The method of gas phase electrodeposition for self-aligned growth and the fabrication of metallic nanobridges has been reported [1]. In addition, metal electrodes growing vertically upwards were also produced with the gas phase electrodeposition [2] for photovoltaic applications. The concept becomes particularly interesting when one considers the upcoming idea of nanoscale interlayer vias (ILV). These are necessary if connections between individual thin chips will be enabled in the next chip generation, so that the computing power can be processed massively in parallel. In addition to the general technological trends for optimizing computing power and upstream production processes, the aspects of materials management and environmental compatibility are becoming increasingly important. Processes with the highest possible material yield are of particular interest. In recent years, gas phase electrodeposition has established itself as a very material-saving method. It enables the locally produced nanomaterial to be selectively captured on the substrate by selective transport in photoresist openings. This achieves a high material yield, which means that expensive materials such as ruthenium or gold, are used economically and efficiently. References [1] Fang, J.; Schlag, L.; Park, S. C.; Stauden, T.; Pezoldt, J.; Schaaf, P.; Jacobs, H. O., Approaching Gas Phase Electrodeposition: Process and Optimization to Enable the Self-Aligned Growth of 3D Nanobridge-Based Interconnects, Adv. Mater. 2016, 28 (9), 1770–1779. [2] Lin, E. C.; Cole, J. J.; Jacobs, H. O., Gas Phase Electrodeposition: A Programmable Multimaterial Deposition Method for Combinatorial Nanostructured Device Discovery, Nano Lett. 2010, 10 (11), 4494–4500. (Note: The presentation shows recent research results which will be published in the second half of 2018.)

Resume : One promising solution to increase the solar cells efficiency consists in developing down-converter layers compatible with the silicon industry which absorb UV photons and convert them into IR ones. To achieve such a goal, rare earth ions doped silicon nitride-based thin films have been deposited by reactive magnetron co-sputtering. This nitride host matrix allows a high RE ions incorporation while avoiding the clustering effect observed in silicon oxide matrices. Moreover, it has been used as an efficient antireflective layer contributing also to a better efficiency of the Si solar cells. Two different co-doping with RE ions have been chosen i.e. Tb3 -Yb3 and Ce3 -Yb3 . The first step of this work is focused on achieving an intense emission of Tb3 or Ce3 ions by optimizing the deposition parameters. In the case of Tb3 ions, the goal is to enhance the coupling between sensitizers and Tb3 ion activator, whereas in the case of Ce3 ions, the optimized 4f-5d transitions allow achieving a direct efficient excitation of the RE ions. A comparison between the excitation efficiency of each co-doped system will be presented. The second step consists in the incorporation of Yb3 ions with an increasing content to optimize the Tb3 /Ce3 -Yb3 ions coupling with the aim at obtaining an intense emission at 980 nm just above the Si fundamental band gap. The excitation mechanisms of Tb3 and Yb3 ions will be discussed. Furthermore, the IR quantum cutting efficiency will be determined by photoluminescence decay time measurements (above 180%). At last, simulations have been performed to find, with help of Bragg mirror, the best density of UV photons trapped in DC layer for a better quantum cutting effect. The additional efficiency has been then calculated.

Resume : Si nanocrystals (Si NCs) with narrow size distributions and mean sizes of 2 to 5 nm are studied to investigate P- and B-doping of ultra-small Si nanostructures. Atom probe tomography (APT) shows that P-atoms are quite efficiently incorporated in Si NCs [1], while B-atoms are less efficiently incorporated [2]. Using photoluminescence spectroscopy (PL), transient transmission (TT) [3] and current-voltage measurements (I-V) it is shown that no free carriers can be detected in P- or B-containing Si NCs. We explain this observation by (i) the significantly increased substitutional formation energy, which incorporates a vast majority of dopant atoms on interstitial lattice sites rather than on Si-lattice sites and (ii) by a significantly increased dopant ionization energy (compared to dopants in bulk-Si) due to quantum and dielectric confinement effects [1-3]. Hence, thermal energy at room temperature is not sufficient for dopant ionization in Si NCs. On the other hand, density functional theory (DFT) suggests that P-/B-impurities on interstitial lattice sites or on the NC-surface give rise to defect states in the energy gap of the Si NCs [1,2], which explains the commonly observed PL-quenching by dopants. [1] D. Hiller, J. López-Vidrier, S. Gutsch, M. Zacharias, K. Nomoto, D. König, Sci. Rep. 7, 863 (2017) [2] D. Hiller, J. López-Vidrier, S. Gutsch, M. Zacharias, M. Wahl, W. Bock, A. Brodyanski, M. Kopnarski, K. Nomoto, J. Valenta, D. König, Sci. Rep. 7, 8337 (2017) [3] D. Hiller, J. López-Vidrier, K. Nomoto, M. Wahl, W. Bock, T. Chlouba, F. Trojánek, S. Gutsch, M. Zacharias, D. König, P. Malý, M. Kopnarski, Beilstein J. Nanotechnol. 9, 1501 (2018)

Resume : Si-based nanoscale devices that exhibit quantum functionalities in their operational characteristics offer new prospects for developments in quantum technologies with areas of application including quantum computing and communications, quantum sensing and metrology. We have developed considerable experience in design, fabrication and measurement of quantum devices in which ion implantation has been a central part of the fabrication protocol. We have demonstrated single donor addressability, spin initialisation and single shot readout for Si devices implanted with one or a few 31P donors. Experiments on devices formed in isotopically-pure 28Si epilayers have shown nuclear spin coherence times for 31P donor qubits in excess of 30 s [1,2]. The challenge for the next generation of devices is to develop fabrication and measurement protocols that allow scale-up to small ensembles of coupled qubits. The recently proposed flip-flop qubit architecture offers the prospect of being able to couple donor qubits over relatively large distances of a few hundred nanometres and with donor placement tolerances that are compatible with ion implantation limitations [3]. To meet the challenge of building devices based on this architecture we have upgraded our deterministic ion implantation method to operate at room temperature. This has required considerable redesign of the on-chip ion impact detection electrode arrangement and development of a device layout that allows for multiple independently targetable construction sites on the one chip to be processed in parallel. Our progress towards meeting this goal will be presented in this talk. At the other implantation fluence extreme we have made devices with nanoscale ring structures that are degenerately doped with either As donors or B acceptors and we have observed novel magneto-transport characteristics at temperatures below the superconducting transition of the aluminium contacts. We will present details of the characteristics of these devices and our understanding of the magneto-transport features. [1] J. J. Pla, K. Y. Tan, J. P. Dehollain, W. H. Lim, J. J. L. Morton, D. N. Jamieson, A. S. Dzurak and A. Morello, A single-atom electron spin qubit in silicon, Nature 489, 541(2012). [2] J. T. Muhonen , J. P. Dehollain, A. Laucht, F. E. Hudson, R. Kalra, T. Sekiguchi, K. M. Itoh, D. N. Jamieson, J. C. McCallum, A. S. Dzurak and A. Morello, Storing quantum information for 30 seconds in a nanoelectronic device, Nat. Nanotech. 9, 986, (2014). [3] G. Tosi, F. A. Mohiyaddin, V. Schmitt, S. Tenberg, R. Rahman, G. Klimeck and A. Morello, Silicon quantum processor with robust long-distance qubit couplings, Nature Comm. 8, 450 (2017).

Resume : Semiconducting nanowires (NWs) hold promises for functional nanoscale devices [1]. Although several applications have been demonstrated in the areas of electronics, photonics and sensing, the doping of NWs remains challenging. Ion implantation is a standard doping method in top-down semiconductor industry, which offers precise control over the areal dose and depth profile as well as allows for the doping of all elements of the periodic table even beyond their equilibrium solid solubility [2]. Yet its major disadvantage is the concurrent material damage. A subsequent annealing process is commonly used for the healing of implant damage and the electrical activation of dopants. This step, however, might lead to the out-diffusion of dopants and eventually the degradation of NWs because of the low thermal stability caused by the large surface–area-to-volume ratio. In this work, we report on non-equilibrium processing for controlled doping of drop-casted Si/SiO2 core/shell NWs with shallow- and deep-level dopants below and above their equilibrium solid solubility. The approach lies on the implantation of either shallow-level dopants, such as B and P, or deep-level dopants like Se followed by millisecond flash lamp annealing. In case of amorphization upon high-fluence implantation, recrystallization takes place via a bottom-up template-assisted solid phase epitaxy. Non-equilibrium Se concentrations lead to intermediate-band Si/SiO2 core/shell NWs that have room-temperature sub-band gap photoresponse when configured as a photoconductor device [3]. Alternatively, the formation of a cross-sectional p-n junction is demonstrated by co-implanting P and B in individual NWs at different depth along the NW core. [1] Peidong Yang, Ruoxue Yan, and Melissa Fardy, Nano Lett. 2010, 10, 1529–1536 [2] Michiro Sugitani, Rev. Sci. Instrum. 2014, 85, 02C315 [3] Y. Berencén, et al. Adv. Mater. Interfaces 2018, 1800101 a)Corresponding author: y.berencen@hzdr.de

Resume : Since few years transistors improvement reached a milestone : innovations in the field of architectures and materials are needed to pursue the downscaling. According to ITRS, Gate-all-Around transistors on vertical nanowires are the most promising candidate for the sub-5nm node. Our aim is to combine the benefits of this architecture with the introduction of a high-mobility channel, namely GaAs, leading to low power, higher performance devices. This innovation induces several challenges toward the integration of a transistor on vertical GaAs nanowires : Fabrication of high density vertical III-V nanowires array on Si as well as the introduction of gate high-k dielectric with low interface defects and low resistive CMOS-compatible source/drain contacts on these 3D nanostructures. Here we will present: - Top-Down approach to pattern high-density arrays of vertical GaAs nanowires on Si with controlled dimensions and localization. - Thin Al2O3 layer by ALD with sulfur passivation, in situ cleaning and annealing exhibiting low value of Dit. HRTEM characterizations coupled EDX quantifications show a perfect uniformity along the nanowires without metallic segregations. - Low resistive CMOS compatible contacts made using Ni-(GaAs) alloy, allowing symmetrical contacts on the top and bottom parts of the nanowires. - All these advances have been integrated in a CMOS compatible process on a conventional Si(100) substrate leading to the realization of new generation of transistors.

Resume : A simple and efficient bottom-up technology for precisely controlling the amount of dopant atoms tethered on silicon substrates is presented. Polystyrene and poly-(methyl methacrylate) polymers with narrow molecular weight distribution and end-terminated with a P-containing moiety were synthesized with different molar mass. The polymers were spin coated and subsequently end-grafted onto nondeglazed silicon substrates. P atoms were bonded to the surface during the grafting reaction, and their surface density was set by the polymer molar mass, according to the self-limiting nature of the “grafting to” reaction. Polymeric material was removed by O2 plasma hashing without affecting the tethered P-containing moieties on the surface.Repeated cycles of polymer grafting followed by plasma hashing led to a cumulative increase, at constant steps, in the dose of P atoms grafted to the silicon surface. P injection in the silicon substrate was promoted and precisely controlled by high- temperature thermal treatments. Sheet resistance and Hall demonstrated effective doping of silicon substrate and were used to determine the effective activation of the injected P impurities.

Resume : I will present emerging strategies for constructing three-dimensional nanostructures whose shapes and symmetries go beyond those of the bulk equilibrium diblock copolymer phase diagram. Photo-thermal methods are used to control block copolymer ordering; ordered layers can be stacked to yield new lattice symmetries. This multi-layered strategy can also be performed in a responsive mode, where each self-assembled layer templates the ones that follow. Finally, I describe how blending allows the self-assembling film morphology itself to be responsive to underlying guide patterns. Taken together, these new motifs represent a toolbox for constructing 3D nanostructures with symmetries and complexity beyond conventional self-assembled morphologies.

Resume : The helium ion microscope (HIM) is a charged particle microscope employing helium ions for probing the sample. In the low dose regime, the HIM operates as microscope, high doses enable material modification and sputtering. Compared to conventional focussed ion beams (FIB) using metal ions like gallium, the HIM offers a very small focal spot size down to 0.35 nm and a strongly localized sputter interaction with the material. In this talk, I will present examples of imaging and local milling of two-dimensional nanostructures with helium ion microscopy. In particular, carbon nanomembranes (CNMs) and graphene will be discussed. CNMs are made by a combination of molecular self-assembly, radiation-induced cross-linking and the detachment of the cross-linked monolayer from its substrate. I will demonstrate that the HIM is particularly well suited for imaging such insulating membranes due to its efficient charge compensation tool. Effects of sample charging, imaging of multilayers and imaging artefacts for CNMs as a model system will be discussed. Furthermore, it will be shown that the focused helium ion beam of the HIM can be utilized to create nanopores in insulating as well as conducting membranes. In CNMs, pore diameters were realized down to 1.3 nm. An analysis of the nanopore growth behaviour allows determination of the profile of the helium ion beam.

Resume : The dewetting process of ultra-thin homopolymeric films has been widely studied in the past years for its potential technological application in coatings for corrosion protection or functional surfaces In this perspective, the possibility to associate the nano-scale pattern typical of the self-assembly (SA) of Block Copolymer (BCP) films to the micro-scale dewetting allows to conceive a new class of materials with improved capabilities and potential application in fields like biological sensing or photonics. In this work the effect of the dewetting process on the SA characteristics (i.e. domain ordering and orientation) of cylinder forming polystyrene-block-poly(methyl methylacrylate) (PS-b-PMMA) BCP films was analyzed. The dewetting of BCP films with thickness between 2 nm and 15 nm was found to be strongly different when induced on Random Copolymers (RCP) systems with different thickness. In particular we considered RCPs having grafting thickness between 2 and 10 nm. When BCP dewets on thin RCPs the ordering of the nanometric cylinders considerably increases, far exceeding the correlation length values obtained in thick continuous BCP films. As a result, circular micrometric droplets composed by a single and defectless grain are generated and randomly distributed on the substrate. The control over the position of the droplets was achieved resorting to large-scale chemical patterns obtained by laser lithography and plasma etching. By properly adjusting the periodicity of the chemical pattern and the substrate wettability it was possible to tune and select the shape of the dewetted droplets in terms of maximum thickness, contact angle and diameter, thus creating highly ordered hierarchical patterns at nanometric scale.

Resume : The self-assembly of block copolymers (BCPs) into ordered nanostructures is a highly attractive bottom-up technique for the creation of arrays of regular nanofeatures on large surface areas. Applying BCP lithography on pre-patterned surfaces makes this technique even more versatile as the directed self-assembly allows for more complex and hierarchical nanopatterns. In this contribution, we present a combination of BCP lithography with nanosphere lithography (NSL). The combination of these two self-assembly techniques will be shown to allow for the creation of ordered hierarchical nanostructures, while maintaining the advantages of low-cost, large-area surface nanopatterning. Applying SEM, AFM, surface energy investigations and TEM, we present the creation of either arrays of hierarchical nanopores or hierarchical concentric nanorings by steering the BCP-surface interactions during self-assembly. The hierarchical nanopores consist of sub-20 nm nanopores site-selectively formed inside arrays of 400 nm-diameter nanohole arrays in different material thin films. Tuning the self-assembly process can be used to generate concentric polymer nanorings inside the circular nanoholes. These tunable hierarchical nanostructures are suitable for advanced lithographical surface patterning or can act as templates for nanoobject positioning.

Resume : Synthesis.Different types of nanowires (NWs) were obtained by template synthesis technique using different polymer matrixes. Metals were deposited using galvanic technique. Cu and Ag were deposited in pure state, while for Fe, Co and Ni different types of deposition were used for obtaining pure, alloys and layered NWs. Emission. Samples of Cu and Ag NWs were used as substrates for deposition of probes in mass-spectrometer. Such structures could be effectively used for desorption and emission of biological molecules-due to small radius of curvature. The dependences of emission intensity on laser intensity and surface density of NWs were investigated. (The last one was found to be non-linear- due to saturation effect). Microscopy and X-ray analysis . It was found that the composition of Two-components-NWs is different from the composition of electrolyte, the effect of “anomalous co-deposition” took place; X-ray demonstrated dependence of crystallinity and defects on deposition. Mossbauer spectra of Fe NWs: it was found that spectra depend on pores diameter. For thick NWs the spectra were the same as for bulk material. For thin NWs the intensity ratio of sextet was different from 3:2:1:1:2:3 due to orientation and presence of defects Magnetic measurements were carried out - all samples are ferromagnetic. For example, Fe-Co samples have “hard magnetic” properties: coercetivity 1100 Oe. Acknowledgements.Work was supported by the FASO (agr. No.007-GB/ChZ363/26).

Resume : Bottom-up grown silicon nanowires are targeted to be applied as nanoscale transducers or building blocks for advanced sensors and devices exploiting their electrical, mechanical and optical properties. Hence, controlled and well-ordered synthesis of silicon nanowires as well as the elucidation of the relevant growth mechanisms is highly relevant and in the focus of research already since the last two decades. So far, well-controlled epitaxial bottom-up synthesis of silicon nanowires by the vapor-liquid-solid synthesis using nanoscale metal catalysts was only realizable on pristine silicon crystal surfaces requiring native oxide removal, e.g. by hydrofluoric acid treatment. In our approach, we achieve well-controlled epitaxial growth of silicon nanowires directly on native oxide covered silicon substrates by using an Al/Au alloy catalyst rather than a pure metal. The catalyst consists initially of an Al/Au film stack (e.g. 5 nm/10 nm) deposited by thermal evaporation onto the silicon-based substrates. The basic idea is here that aluminum will disintegrate first the native silicon oxide by forming Al-O compounds while simultaneously forming an AlAu2 liquid alloy droplet that precipitates the Si nanowire in epitaxial relation with the silicon substrate. The Al/Au-catalyzed silicon nanowires were successfully grown in an epitaxial manner by using SiH4 as precursor gas within a temperature range of 550 °C and 600 °C, which is above the eutectic temperature of the AlAu2 alloy of about 487°C. The crystallinity of the silicon nanowires as well as the catalyst composition were examined by scanning electron and high resolution transmission electron microscopy. The nanowires are single-crystalline and grow in <111> direction similarly to Au- and Al-catalyzed silicon nanowires as reported elsewhere. The Al/Au ratio of catalyst, present at the nanowire tip, fits to the AlAu2 phase. By utilizing this growth strategy, well-ordered silicon nanowire arrangements were created on silicon <111> and <100> substrates. Notably these nanowires show also a high degree of perpendicular branching and self-welding. This might enable new strategies for the assembly of unique nanostructured materials and 3D nanowire electronic systems.

Resume : The bottom-up synthesis of crystalline silicon nanowires (SiNWs) by using a variety of metal catalysts (Au, Ag and Pt) was extensively studied during the past decades. Here, SiNWs were frequently discussed as nanoscale building blocks for various applications, ranging from electronics to sensing and even to photonics. However, silicon contamination by the metal catalyst is an omnipresent issue because already minute concentrations of metal atoms in silicon can degrade the electronic and optical properties by the generation of deep trap states. Hence, alternative synthesis methods are required but must be established. Here, we present a metal catalyst-free approach to reproducibly grow SiNWs in an in-house built gas phase reactor system at about 680°C using SiH4 and H2 as precursors. The process is expected to be triggered by reactive-oxide as per the so-called oxide-assisted growth mechanism, which was proposed elsewhere. Based on our experiments we will discuss that SiOₓ clusters or nanoparticles act as effective trigger points for a crystalline SiNW growth. Silicon nanoparticles are consistently embedded in the nanowire tip and already present during the SiNW nucleation. We show that plain KOH treatment of silicon can be utilized to generate reliably these trigger points in dependence on the KOH concentration and Si substrate crystal orientation. Consequently, local KOH substrate pre-treatment allowed to confine the nanowire growth to these areas only.

Resume : Among many different types of nanostructures, magnetic nanoparticles are probably the most widely used one. For many applications, thermal stability of magnetic nanoparticles, is very important subject. This is especially crucial when they are considered to be applied in magnetic hyperthermia treatment, for example. It was observed that thermal evolution is influenced by the fabrication process. Therefore, series of core-shell ferrite nanoparticles obtained by thermal decomposition of iron (III) acetylacetonate were doped with a various amount of Co2+, Mn2+, or Ni2+ ions. This way prepared nanoparticles were thermally treated at 450 or 500 °C for 24h, to see doping effect on the oxidation process of magnetite/maghemite crystalline structure. Nanoparticles before and after thermal treatment were measured by transmission electron microscopy, energy dispersive X-ray, X-ray diffraction, and Mössbauer spectroscopy to get reference and evolution stage. Conducted studies show that doping of different 3d element prevents the oxidation process of ferrite nanoparticles what, therefore, gives new possibilities of their application. The range of restriction depends on the element and its amount. The work was partially financed by EU funds via project with contract numbers POPW.01.03.00-20-034/09-00, POPW.01.03.00-20-004/11-00 and by NCN found, project number 2014/13/N/ST5/00568.

Resume : The unrecognized segregation of metallic ferromagnetic nanocrystals in dilute ferromagnetic semiconductors (DFS) is an important issue which, if not recognized, can lead to misleading conclusions. (Ga,Mn)As – a canonical DFS material is an excellent model system to study the intentionally induced phase segregation of magnetic, Mn-rich nanocrystals inside the GaAs semiconductor matrix. Even moderate thermal annealing (300 – 400 C) causes decomposition of (Ga,Mn)As solid solution into ensemble of MnAs nano-inclusions randomly dispersed in the GaAs lattice. Dimensions of such MnAs nanocrystals (NCs) depend on the annealing procedure details and are in the range of 5 – 50 nm. NCs can occur either in hexagonal phase, typical for MnAs bulk (larger nanocrystals), or in the cubic phase imposed by the surrounding zinc-blende matrix (smaller nanocrystals). We focus on annealing induced phase segregation in wurtzite (Ga,Mn)As crystallized by molecular beam epitaxy (MBE) as thin shells of wurtzite (In,Ga)As nanowires. Here both MnAs and wurtzite GaAs share hexagonal structure hence only hexagonal MnAs nanocrystals occur. Moreover nanowire geometry allows for controlling the distribution of nanocrystals both in radial and axial direction. In parallel to the samples annealed directly after the MBE growth we have also performed in-situ annealing experiments in the transmission electron microscope, enabling recognition of the beginnings of the MnAs phase segregation process. This work has been supported by the National Science Centre (Poland) through the projects No: 2014/13/B/ST3/04489, 2016/21/B/ST5/03411 and 2017/25/N/ST5/02942.

Resume : Magnetic nanoparticles (NPs) are a well-known and attractive class of materials, with applications in different fields, going from catalysis to biomedical applications. Core/shell NPs represent a popular choice among the different compositions and morphologies under constant development and improvement, since they combine the properties of the core (inner material) and those of the external shell (outer material). Here, we show the preparation of different colloidal bi-magnetic core-shell systems, followed by a cation exchange (CE) procedure to focus on the role of the host NPs crystal structure. To achieve this goal, we performed in-depth morphological, structural, spatially resolved chemical and magnetic behavior analyses of the initial and cation-exchanged NPs. We compared spherical magnetite and wüstite NPs with the same diameter. Then, we performed the doping with Co or Mn by a post-synthetic CE protocol to obtain a mixed Fe/Mn or Fe/Co shell, without affecting the shape and size of the original NPs. Then, the crystal structure of the two phases (non-defective for magnetite, defective for wüstite) was the only variable among the NPs populations that affected the CE, leading to higher percentage of the doping cation (Co or Mn) for wüstite. In turn, this gave rise to dramatic effects in terms of magnetic behavior of the final NPs.

Resume : Nanocomposites are considered the most propulsion materials with extraordinary potential for functional applications in top-level domains from the biomedical, optoelectronic to the aerospace industry. This paper present the main steps for ex-situ synthesis and characterization of nanocomposite materials based on a PMMA matrix and an inorganic oxide (Y2O3) at different concentrations in the matrix and in the presence of solvent associated with the matrix. The influence of the content of Y2O3 particles on the morphological properties and structural of synthesized nanocomposite materials was study by field emission scanning electron microscopy FE-SEM, FTIR spectrometry and X-ray diffraction. The SEM images of the Y2O3 nanoparticles tend to form aggregates, but by proposed method for embedding in the PMMA matrix it has been found a good dispersion, with the formation of small agglomerates depending on the Y2O3 particle content. The FTIR spectra for all samples confirm bands below 600 cm-1 characteristic metal-oxygen (Y-O), but also the absorption bands characteristic of the polymer matrix. X-ray diffraction analysis (XRD) show the phase types, diffraction patterns and the average crystallites dimension ranging between 20-90 nm. Compared to nanoparticles, the XRD of nanocomposites does not reveal any structural change. Following the obtained results were created premises for applications of the nanocomposite materials in the aerospace and other related fields.

Resume : Conversion of mechanical energy into electrical energy and vice versa in piezoelectric materials have a wide range of applications in energy harvester, sensors, and actuators. Antiparallel stacking sequence in semiconducting transition metal dichalcogenides (TMDs) bulk crystal makes it centrosymmetric thus nonpiezoelectric. Contrary, piezoelectricity in mono or odd layers arises from broken inversion symmetry in many two-dimensional (2D) TMDs can be utilized for efficient exfoliation processes. Owing to distinctive physical properties and emerging applications, 2D tungsten disulfide (WS2) has become one of the most extensively studied TMDs in the recent years. Here we demonstrate an experimental process to improve exfoliation efficiency of WS2 using an external electric field. We successfully able to thin down and enhance the exfoliation efficiency by exploiting the intrinsic piezoelectric nature of WS2. The nanosheets produced in the liquid phase by our developed method are relatively small in size and free from any apparent defects. The developed approach can lead to new possibilities of large-scale production of non-centrosymmetry 2D layered materials for the applications in electronics, optoelectronics, and energy harvesting devices.

Resume : A self-oil cleaning surface in-air and underwater was presented on hygroscopic fabrics having the high aspect-ratio (AR) nano-hairy patterns. The nanopatterns with a wide range of ARs, defined as the ratio of the height over the width, were formed on the cellulose fabric by selective plasma etching with the different gas flow rate and treatment duration. Pristine fabrics show low adhesion for low viscous crude oil, but very high for high viscous Bunker C oil in water. However, the nanostructured cellulose fabrics with high AR of more than 1.4 showed the significant decrease of adhesion for bunker C oil due to low solid fraction, showing easy oil cleaning underwater and at the air-water interface due to faster hydroscopic nature. Performed by a cross-sectional analysis under cryo condition, it was found that unlike the oil residues strongly adhered on the pristine, an oil residue on nanostructured cellulose fibers were found to have high wetting angle and low adhesional contact on water film coated nanostructures. Self-oil cleaning test was also performed in-air, revealing that the continuous flow of water droplets lift oil up and easily cleaned the oil-contaminated surface with nano-hary. As worked in-air and underwater, the hygroscopic sieve with the self-oil cleaning surface showed the high efficiency and robust in oil recovery capacity from oil-water mixture over time.

Resume : TiO2 has three naturally occurring polymorphs, i.e., rutile, anatase and brookite. The synthesis of pure brookite is generally much more difficult than that of pure anatase or rutile. Our group investigated conditions of Mg2TiO4 preparation and hydrothermal conversion to brookite. Kozawa et al. reported hydrothermal conversion of Mg2TiO4 into brookite TiO2 under mild condition. Machida et al. reported facile synthesis of >99% phase-pure brookite TiO2 by hydrothermal conversion from Mg2TiO4. Size and shape of particles affect material properties. Here, we intend to control the size and shape of brookite nanopowders. Brookite TiO2 powders were synthesized by the hydrothermal conversion method using Mg2TiO4 as a precursor. MgCO3 (basic) and TiO2 powders were wet ball-milled at stoichimetric 2:1 ratio in ethanol for 2 h, and then, the mixed slurries were vacuum dried and the powders were placed in an oven at 80°C for 1 h. After that, the powders were calcination at 1270°C for 2 h in air. This precursor powders and HCl aq. solution were put into an autoclave, and hydrothermal conversion was conducted. Microstructure, particle size, and specific surface area were evaluated. Additional ball-milling effect was also studied.

Resume : Surface-enhanced Raman scattering (SERS) provides dramatically intensified Raman signals for the molecules near metal nanostructures. However, the surface of the metal nanostructure is prone to contamination by adhesive proteins for most biological samples, which restricts the use of SERS. The aim of this study is to design SERS-active microgels with molecular selectivity and signal reproducibility by embedding highly-concentrated gold nanoparticles in the matrix of hydrogel microspheres. With a capillary microfluidic device, water-in-oil-in-water double-emulsion drops were prepared, of which water core contains gold nanoparticles and hydrogel precursors. To concentrate gold nanoparticles, water was pumped out through the oil shell by imposing positive osmotic pressure. The concentration of nanoparticles increases in a factor of 10-50 in the absence of aggregation. Finally, microgels containing highly-concentrated gold nanoparticles were suspended in water after polymerizing hydrogel precursors and rupturing the oil shell. As the homogeneous hydrogel matrix allows diffusion of molecules smaller than mesh size, gold nanoparticles were free from protein contamination. At the same time, microgels also provided high reproducibility of Raman intensity as nanogap-forming gold nanoparticles were evenly embedded in the whole volume of microgels. Therefore, the microgels are useful for direct detection of small molecules dissolved in complex biological fluids such as blood and urine.

Resume : Vanadium dioxide undergoes a reversible metal-insulator phase change near 68°C. This is close to room temperature and around working temperature of many electronic devices. Thus, it is possible to modulate the transition by some energy transfer by external electric, magnetic or optical means. This transition is often recognized for the change of several orders of magnitude of the conductance and the optical absorption. Consequently, VO2 can be used for electric, optical or electromagnetic switches. Other applications can exploit the optical properties within this transition region to control and tune the refractive index between its insulating and metallic states. Additionally, electron beam evaporation is attractive as a large area, cost-effective and low temperature method of deposition. Phase transitions undergone by VO2 thin films deposited by electron beam on a (100) boron-doped Si substrates when heated from room temperature (RT) up to 500ºC in air are investigated by Photoluminescence (PL), Raman and X-ray photoelectron spectroscopy (XPS). The results show that the films undergo several intermediate phase transitions between the initial VO2 monoclinic phase at RT and the final V2O5 phase at 500ºC. Peak frequencies, full-width half-maxima, binding energies and oxidation states from the PL, Raman and XPS experiments are reported and analyzed for all the phases encountered in the VO2 thin films.

Resume : Electromigration is one of the main reason for failure of conducting paths (i.e., interconnects) in microelectronics. A high electron flux passing through interconnects lead to displacement of the conducting material at atomic scale. Voids and hillocks form at the cathodic and anodic sides, respectively. Temperature plays a crucial role in the mass transport leading to device failure. A new hot topic on developing 2.5D integrated circuits using through-silicon vias has been investigated by different groups. The current study focuses on a systematic investigation of base vias materials such as Al and Cu. Statistic measurements obtained on predefined 2D wires are used as background for development of new materials. The crystallographic particularities of the conducting paths are analyzed and the initial phase of the electromigration mechanism is described as depending on the grain boundary stress induced evolution. The blocking effect of anodic oxide growth has been studied on void formation and pinning on the conductor surface. A combinatorial approach is used for fabrication of Al-Cu thin film alloys by sputtering co-deposition. A wide compositional range is screened and electromigration resistance is assessed along the compositional gradient. The effect of surface oxide on the conductor performance at high current densities is compositionally studied. Additionally, the effect of temperature is studied on the mass transport and the best Al-Cu vias alloys are identified.

Resume : Passive cooling technologies are of great interest in the current climate to address the problem of the growing global energy consumption, 15% of which is accounted for by modern cooling systems [1]. Radiative cooling based upon optimising thermal emissivity of a surface in the atmospheric transparent region of the electromagnetic spectrum is one such technology which has great potential. One method for increasing the emissivity of a device is to out-couple surface phonon polaritons (SPhPs), which exist in polar dielectric materials such as SiO2, via means of diffraction from a surface periodic structure. Diffracted SPhPs can out-couple into free space as infrared radiation; a mechanism which evacuates thermal energy [2]. Self-assembled opals present an easy method to create large area and scalable 2D nano/micro-structured surfaces. Here we present a theoretical study using an in-house developed rigorous-coupled-wave analysis (RCWA) code in order to predict the optimal opal structure which will maximise the emissivity in the atmospheric transparency window for the greatest range of angles. We investigate the effect of creating both opal and inverse-opal structures as well as ways to maximise the material properties in order to predict broadband thermal emitters with high cooling power. [1] Y. Joshi, & P. Kumar, Energy efficient thermal management of data centers. (Springer Science & Business Media, 2012). [2] A. R. Gentle & G. B. Smith, Radiative heat pumping from the Earth using surface phonon resonant nanoparticles. Nano Lett. 10, 373–379 (2010).

Resume : Circularly polarized luminescence (CPL) refers to differential emission of left- and right-handed circularly polarized lights. CPL finds increasing photonic utility, including imaging applications such as 3D optical displays, enantioselective sensing, and quantum informatics. Despite the promising utility in 3D electroluminescence, reports on molecules showing circularly polarized phosphorescence (CPP) remain sparse in the literature, and the majority of reported compounds suffered from low values of dissymmetric factors (|glum|) and photoluminescence quantum yield (PLQY) for CPP emission. We have demonstrated the sergeants-and-soldiers strategy for amplification of both |glum| and PLQY values. A pairs of enantiomers of homochiral Pt(II) complexes having the Masamune Box ligands (denoted as (R)- and (S)-PtBox) served as the sergeants, and an achiral Pt(II) complex having 4,4?-bis(nonyl)-2,2?-bipyridine (denoted as PtN) was employed as a soldier. Spontaneous formation of co-assemblies of the sergeant and soldier was observed, upon drop casting of a solution containing PtBox and PtN (2:5, w/w). The co-assemblies exhibited Cotton effects at the metal?metal-to-ligand charge-transfer absorption band of PtN (|gabs| = 0.02), suggesting exciton coupling to be responsible for the chiroptical effect. Finally, strong CPP was observed from the co-assemblies with amplification in both PLQY (0.006 (PtN assembly) ? 0.01 (PtBox:PtN co-assemblies)) and |glum| (< 10?3 (PtBox) ? 0.05 (PtBox:PtN co-assemblies)). Spectroscopic studies suggested that such enhancements were ascribed to chiral amplification and intra-assembly energy transfer of PtBox.

Resume : Exploding foil Initiators (EFIs) or chip slapper detonators offer superior timing and safety performance compared to other means of initiating detonation in high explosives. EFIs consist of a thin conductive foil that is heated and vaporized by a high-voltage, high-amperage electric current. This vaporizing metal accelerates a thin plastic flyer to several km/s across a small (~100 um) gap. This flyer then strikes, and shock initiates an explosive. The exploding foil is the key unit in the energy conversion process, and the common material used is copper. However, the conversion rate is low. Due to the complete solubility across the phase diagram without any intermetallic phases or amorphous formation region of Cu/Ni multilayers, this work outlines a way to improve the energy conversion rate by tuning the electrical exploding properties of multilayered Cu/Ni composites with controlled bilayer thickness. The burst current-voltage curves of the Cu/Ni multilayer with a unique bilayer thickness under different loading voltages are obtained. And a model is built to analyze the electric explosion process. Finally, the velocity of the flyer driven respectively by Cu/Ni multilayer, Cu foil and Ni foil is measured with DISAR.

Resume : Phosphorescent Pt(II) complexes constitute an important class of dopants for organic light-emitting devices. We investigated influences of electronic control on the tetradentate ligands in a series of cyclometalated Pt(II) complexes. Our synthetic control involved stabilization of the highest occupied molecular orbital (HOMO) of Pt(II) complexes through employing a methylene linkage in a tetradentate ligand. In addition, electron-donating methyl substituents were introduced in the ligand for destabilization of the lowest unoccupied molecular orbital (LUMO). Three Pt(II) complexes having di(3-(pyrazol-1-yl)phenyl)methide (PtSN1), di(3-(3-methylpyrazol-1-yl)phenyl)methide (PtSN2), and di(3-(4-methylpyrazol-1-yl)phenyl)methide (PtSN3) tetradentate ligands were synthesized and characterized. PtSN1 displayed blue phosphorescence emission with an emission peak wavelength of 440 nm and a quantum yield of 0.32. Unexpectedly, PtSN2 and PtSN3 having methyl substituents in their tetradentate ligands showed dual emission (PtSN2, peak wavelengths = 382 nm and 437 nm, quantum yield = 0.06; PtSN3, peak wavelengths = 384 nm and 442 nm, quantum yield = 0.09). Photoluminescence lifetimes of the dual emission were in the nanosecond and submicrosecond ranges, indicating emergence of fluorescence and phosphorescence from a single molecule. The results present that the structural control has profound influence on the phosphorescence behaviors.

Resume : The surface of a nanocrystalline zinc oxide (ZnO, instead of TiO2) layer deposited on FTO supporting material and sensitized by a novel metal-free organic dye is used as photoanode to deposit for the first time by in situ electro-assisted photopolymerization (PEP) a conducting polymer (CP) which constitutes a solid state hole transporting material (HTM). The as obtained photoanode constitutes a solid state dye sensitized solar cell (ssDSSC) after the deposition on the HTM of a gold thin layer as counter electrode. The obtained ssDSSCs show relatively high efficiencies (? = 0.66 %) with respect to ZnO based sDSSCs produced until now (0.13% reported by Lee et al. [1] and using casted Poly 3-hexylthiophene as HTM) and knowing that the maximum efficiency is 1.7% obtained for ssDSSCSs based on CuSCN used as HTM. [2] Moreover, our ZnO based ssDSSCs show long term stability (more than 2 years) when used under diffuse light conditions. The improvement of these preliminary results will be also presented and discussed. 1- Lee, T.-H.; Sue, H.-J.; Cheng, X. Nanoscale Res. Lett. 2011, 6 (1), 517. 2- Desai, U. V.; Xu, C.; Wu, J.; Gao, D. Nanotechnology 2012, 23 (20), 205401.

Resume : Resistive random access memory (ReRAM) is considered as a promising candidate for next generation non-volatile memory. However, selector devices are required to suppress the sneak current in the cross-point array. Oxides with metal?insulator transition (MIT), such as NbO2 is widely investigated for selector devices but the mechanism is not fully understood. Also Nb2O5 was reported to show ReRAM switching property. It was reported that 1S1R(Selector+Memory) device can be fabricated by using Niobium oxide bi-layer (NbO2/Nb2O5) structure. In our study, we deposited a single 30 NbOx films by reactive DC magnetron sputtering in order to fabricate the Pt/ NbOx/TiN (MIM) device. For detailed information, we measured chemical composition of the NbOx film by the XPS with depth profiling. For the electric characterization of devices, the compliance current during the forming process was set to 1 mA to prevent film from hard-breakdown. During the subsequent switching process, the compliance current was changed from 1 mA to 10 mA. In the low current region (~1 mA), devices showed threshold switching characteristics. However, when compliance current was set as 10 mA, the switching behavior was changed into the bipolar resistive switching. In the certain compliance current range, the devices exhibit 1S1R switching characteristic. We conclude that operation characteristics of MIT affects by current and 1S1R devices could be fabricated with a single Niobium oxide layer.

Resume : One-dimensional (1D) nanostructures (nanowires (NWs), nanorods (NRs), and nanotubes (NTs)) provide countless advantages in various opto-electronic device applications owing to their unique properties such as light trapping function, low reflection, large junction area and effective charge collection. Recent studies has shown that Si NWs can be employed for a wide range of electronic and opto-electronic device applications. Results have revealed that Si NWs with several tens of micrometers length not only show the excellent light trapping properties but also an efficient charge transport in their device applications. It is a well-known fact that the synthesis of Si nanostructures in a controlled fashion is a prerequisite for many device applications. Several top-down and bottom-up methods have been developed so far for the synthesis of Si NWs. Among them, electroless etching (EE) ( a solution-based route) has attracted a great deal of attention in recent years due to many advantages it offers. This technique, for instance, allow us to fabricate large area single crystalline well-oriented Si NWs in a simple and cost-effective manner. It is known that by adjusting some growth parameters such as growth time, growth temperature and precursor concentration it is possible to produce Si NWs with different morphology and aspect ratios. In this study, therefore, the effect of growth parameters on the quality of the synthesized Si nanowires (NWs) was investigated in detail. It was clearly observed that the lengths of the Si nanowires increase with the increasing of etching time. The lengths of the Si NWs etched at 50oC for 10 min and 30 min were found to be ~1.62 ?m and ~3.48?m, respectively. The growth temperature of the etching solution is another parameter that has a direct influence on nanowire length and density, since it changes the kinetics of the reduction oxidation reactions. It was found that the length of the Si NWs is linearly proportional to the solution temperature. In addition to these, it was also revealed that with increasing AgNO3 concentration there is a systemeatic increase in the length of grown nanowires as wel as a significant modification in the morphology of Si nanowires. The only drawback of this technique is that the fabricated NWs are randomly distributed over the Si-wafer. To eliminate this and make the fabrication of the well-ordered Si-NWs possible a pattarned metalic layer (in a desired geometry) is required to initiate a selective etching. We have applied the polysytrene nanosphere lithography for the transfer of a metalic pattern on Si-wafer via deposition of Ag by thermal evaporation technique to achive the aforamentioned goal. Therefore, in this study, the optimization parameter for transfering of well-ordered monolayer nanospheres on Si-wafer for the construction of well-ordered Si NWs was also discussed in detail.

Resume : In recent years, silicon quantum dots (Si-QDs) embedded in dielectric matrix have attracted much attention for the applications in fields such as data storages or optoelectronics (Si-based light emitters and next generation all-Si based solar cells). In this work we performed a detailed comparative study of the structural, optical and photoluminescent properties of Si-QDs formed in annealed Si/SiNx and Si/SiO2 multilayers. Samples consisting of up to 121 alternating sublayers of silicon and silicon nitride or silicon oxide as dielectric barrier sublayers have been grown by means of PECVD with a substrate temperature of 250°C using silane, nitrogen and nitrous oxide as precursor gases and post-annealed between 600-1100°C. TEM, XRD, Raman, FT-IR, UV-Vis and PL techniques were used to characterize the prepared superlattices. The dependences of the photoluminescence, structural and chemical bonding characteristics of Si-QDs on the dielectric barrier material and thickness were investigated. The cross-section TEM, XRD and Raman measurements confirms the formation of Si-QD in the range 3-20 nm. Raman spectra show the presence of peak at the position around 517cm-1 corresponding to Si-QDs. FT-IR measurements indicate the disappearance of hydrogen bonds at the temperature of 600°C. It was found that the size of the formed Si-QDs was dependent on the annealing temperature as well as the sublayer thickness. Columnar growth and evolution of wavy interface morphology was discussed.

Resume : Rare-earth sulfides (RES) are gaining significant attention in the research community as they are highly interesting for a broad field of applications such as photovoltaics, thermoelectrics or spintronics owing to their interesting functional properties. Reports on research related to RES in thin film form have been limited and especially their growth via vapor phase deposition such as metalorganic chemical vapor deposition (MOCVD) has hardly been explored although this technique has a huge potential for large scale applications. The lack of suitable RE precursors has been the main cause for the slow progress made in this field. Our focus was to develop an MOCVD process for Nd2S3 which is a highly interesting material system possessing a band gap between 1.9 eV and 2.5 eV for ? and ?-Nd2S3 phases, respectively. For photovoltaics, ?-Nd2S3 is considered as an alternative and promising photoabsorber material for novel lead/cadmium free solar cells. For the first time we were able to establish a novel MOCVD process for neodymium sesquisulfide (Nd2S3) thin films in the range of 400 °C to 600 °C. The film characteristics were investigated via X-ray diffraction, atomic force microscopy, scanning electron microscopy, Rutherford backscattering spectrometry/nuclear reaction analysis and X-ray photoelectron spectroscopy. Furthermore, UV/Vis and photoluminescence measurements were performed and the results demonstrated the potential of Nd2S3 in optoelectronics.

Resume : Self-assembled soft materials such as block copolymers (BCPs) thanks to their extraordinary ability to assemble into ordered periodic structures are excellent templates for synthesis of ordered nanomaterials. In our research, we combine an ultra-fast method of BCPs directed self-assembly called Laser Zone Annealing (LZA) with layer-by-layer processing to obtain diverse morphologies, where nanoscale order can be tuned by a choice of block copolymers and by processing conditions. The resulting novel BCPs architectures can be used as templates for the conversion to multi-layered organic nanostructures with precise spatial control over their chemical composition; optimized for the targeted function. It is possible to create multi-functional layers where one of them composed of metallic NWs is a current conductor responsible for heating or voltage-biasing and another could be an active semiconducting sensor. In particular, we are investigating a synthetic strategy towards the BCPs-derived chemical sensors and multi-functional catalytic arrays. The synthetized NW arrays were investigated by several techniques, including Atomic Force Microscopy and Scanning Electron Microscopy.

Resume : Two important classes of soft materials - liquid crystals (LCs) and block copolymers (BCPs) share a fascinating ability to self-assemble into complex supramolecular structures. However, the size of characteristic motifs or domains formed in these two systems is quite different. While BCPs in general are forming larger domains composed of multiple polymeric chains the assemblies in LCs form on molecular level and thus are much more prone to rearrange in response to external stimuli. Our approach relies on hierarchical combination of the two materials. Larger scale (20-100 nm) BCP periodic nanostructures serve as a structural scaffold and for the orientation and growth of small-molecule LC domains. Due to the structural rigidity of the BCP films below their glass transition temperature, they can be used as robust mechanical support for much softer LC phases and guide their alignment. Conversely, the fluidity of the LC phase resulting from the mobility of the mesogenic molecules grants the hybrid material with an ability to quickly respond to the external biases. We demonstrate how, after the annealing and orientation in a process called Laser Zone Annealing (Nature Commun., 2015, 6), the surface of the BCP film can be chemically modified to promote the interactions with the nanotubules derived from B4 phase LCs (Chem. Commun. 2013, 49 (30), 3119?3121) either by graphoepitaxial or chemoepitaxial mechanism. In the latter case, nanowires obtained after the conversion of the block copolymer are acting as a scaffold to nucleate the growth of the nanotubes. In the former case, the NWs can be additionally grafted with adhesion-facilitating molecular layer which provides the proper boundary condition for the growth of the nanotubes.

Resume : Among nanomaterials are layered nanowires (NWs), (consisted of alternating layers of magnetic and nonmagnetic metals) are of great interest ?due to some effect- for example the "giant magnetic resistance" (GMR). New technique of obtaining of layered NWs was proposed. Generally the method of obtaining heterostructural nanowires is based on template synthesis techniques, using the difference between the equilibrium potentials of Ni and Cu electrodeposition. In this research porous template - nuclear track membrane was used; the dependence of the deposited substance on the potential was investigated and optimal regimes for layer-by-layer deposition was proposed. So, the Cu/Ni nanowires with different geometry and composition parameters were obtained. NWs were examined by TEM: Map of elements demonstrated the existence of layers of Cu (almost pure) and alloy Ni-based alloy (83%Ni and 17%Cu). New approach - the passed-charge measurements- was proposed for control the thickness of layers. The X-ray method was used: it was found that crystallinity of both types of layer depend on pores diameter and deposition voltage. The correlation between cell-parameter, elemental composition and deposition voltage was investigated. The TEM-technique was used for testing the interfaces between Cu and Ni layers. Acknowledgements. Synthesis of NWs and SEM (in part)- the state task FNIC "Crystallography and Photonics" of RAS - supported by the FASO (agr. No.007-GB/ChZ363/26), RFBR grant No.18-32-01066.

Resume : New type of magnetic nanomaterial ? ?layered? and ?alloys? nanowires (NWs) seems promising due to variable magnetic properties and wide orange f potential applications: sensors, nanomagnets, units for magnetic field measurements (based on GMR-effect). The method of obtaining homogeneous and heterostructural NWs is galvanic deposition. In this work layered Cu/Ni nanowires and alloyed Fe-Ni were grown. The deposition curves were obtained, X-rays and SEM were done. The optimal conditions for obtaining of NWs were found. The effect of the external magnetic field (MF, 0.25 T), applied during the deposition of magnetic metal (applied to growing sample by different poles)-was investigated. Layered Cu/Ni NWs- Electrodeposition of NWs with alternating metals in the "standard mode" was studied. The optimal potentials for the deposition were found: for Cu-0.8V and for Ni-1.8V. Then the external magnetic field (MF,0.25T) was applied to growing sample by different poles. It was shown that MF accelerate the galvanic process and leads to formation of the ?cavities? in Ni layers. Alloyed Fe-Ni. The external MF leads to acceleration of deposition; the applying of south pole leads to more pronounce effect. MF (north poles) leads to formation of NWs with crystallographic texture with 111 preferred direction. Acknowledgements. Synthesis of NWs and SEM (in part)- the state task FNIC "Crystallography and Photonics" of RAS - supported by the FASO (agr. No. 007-GB/ChZ363/26).

Resume : The work is devoted to ascertainment of the regularities for thermostimu-lated formation of the phase composition and structure of CoSb3-scutterudite-based films deposited by the vacuum condensation method, as well as the effect of the nanoscale factor on their thermoelectric properties. It is determined that the change in the substrate temperature during the deposition of nanoscale Co-Sb films in the concentration range of (65?81) at.% Sb allows to regulate the structural state. During the deposition on substrates at a room temperature, an X-ray amorphous state with an extended region for existence of the CoSb3 (75?80) at.% Sb phase after crystallization and further heating is formed. When the substrate temperature increases up to 200?C, a crystalline state forms and regulari-ties of phase composition formation in Co-Sb films are characterized by a sequence which is analogous to the phase equilibrium diagram for the bulk state of the Co-Sb system with the CoSb3 phase formation at 75 at.% Sb. It was determined that the presence of the nanoscale factor (the single-phase crystalline structure of CoSb3 scutterudite with an extended area of existence in the film with increased structural defect due to the sublimation of antimony and reduction in the grain size) causes an increase in the thermoelectric efficiency coefficient of Co-Sb films in 8 times as compared to the bulk material. This has a practical importance when these materials are used for providing the autonomous power supply for low-power electronic devices and creating film coolers in the elemental base of the nanoscale range for computer equipment and infrared sensors.

Resume : Among self-assembled soft materials, block copolymers (BCPs) are perfect candidates to fabricate nanomaterials with tailored structure, because of their ability to form a variety of periodic morphologies. Moreover, periodic inorganic structures with various size, composition and functionality can be obtained, by selecting and tuning the composition of a BCP and, subsequently, a method of chemical conversion of the polymer template. One of the most efficient methods of ordering BCP thin films is Laser Zone Annealing (LZA), which combines two major practical advantages ? very short time of a processing and high quality of structural order in produced BCP templates. In this report, we focus on cylinder-forming BCPs which are uniaxially aligned by LZA. In our experiment, we have successfully obtained heterostructures of two aligned layers of BCP on silicon, crossed at different angles. Each layer was further converted, either to a noble metal or an oxide nanostructured replica. Afterwards, parameters of such heterostructures were investigated by several techniques, including Atomic Force Microscopy and Scanning Electron Microscopy. These nanostructures may serve as a very efficient miniaturized chemical sensor with several advantages compared to their conventional counterparts such as high sensitivity, fast response and low power consumption.

Resume : Ensembles of ?two-parts? nanowires (NWs) arrays were obtained by electrodeposition of two metals into the pores of track matrices (TM: PET, pore diameter 50 - 500 nm and density 10**8). Two metals (of iron group -Fe, Co, Ni) were subsequently deposited from two electrolyts, using ?two-bath? method. Before and after the deposition of metals into the pores, the ?flat? contacts at the surface of the sample (polymer film) were deposited (At least one of these contact must be transparent for electromagnetic (EM) irradiation). It is known that electromagnet waves of THz frequency could be generated when high-density current passes through the contact of two metals with different magnetic properties. In our case it was the contact between two parts of each NW in ensemble. We found that THz radiation could be generated when current passing through such samples. A sinusoidal current with a fixed voltage of 1, 2 and 3 V was applied to the sample, after which the change in background of generated radiation was recorded using Goley?s cell. The best results were obtained for current passed from Fe to Ni parts in ensemble. Thus, the presented results confirm the possibility of constructing spin-injection generators on the base of the nano-structures- considered NWs, formed in polymer track matrix.

Resume : Modelling of thermoelectric properties of noble d-metallic nanoclustered materials was carried out. Semiclassical thermoelectric transport coefficients had been obtained from DFT band structure calculation. ?onsiderable increasing of Seebeck coefficient had been received numerically, principally coinciding with experimentally observed trends of nanoclusters properties. In order to develop highly efficient thermoelectric materials relationship of structural, electronic and thermoelectric properties of d-metallic nanoclusters and nanostructures is discussed.

Resume : Composite structure p - (Ag2O - Hg1- xCdxTe (x ~ 0.223)) fabricated by Ag+ ion bombardment of the semiconductor target with oblique-incidence geometry (angle of incidence ? = 30°, 45°) are presented. The penetration of the Ag+ ions in the HgCdTe stimulates the formation of nanostructured surface. Analysis of the chemical compounds of Ag inclusions in Hg1-xCdxTe (x ~ 0.223) was studied using XPS spectroscopy and Raman scattering. It was found that in the range of nanoscale, arrays of holes and mounds on Hg0.777Cd0.223Te (111) surface as well as the polycrystalline Hg1?xCdxTe cubic phase with alternative compound (x~0.20) has been fabricated using 100 keV ion beam irradiation of the basic material. Charge transport investigation with non-stationary impedance spectroscopy method has shown that a nanostructured surface of HgCdTe has passive inductive properties. It is assumed that nanostructured surface with silver inclusions plays the role of nanoantennas with Non-Foster impedance matching. Composites that integrate the nanostructured ternary compound (HgCdTe) with metal-oxide (Ag2O) inclusions produced by ion implantation extend the spectral sensitivity region of the basic semiconductor of infrared technology to the MM range.

Resume : Ordered arrays of plasmonic nanostructures separated by a dielectric spacer from a metallic layer supporting propagating plasmons demonstrate a rich tunable spectrum of interacting electromagnetic excitations. The material, lateral size and height of the nanoparticles, the type and pitch of the lattice as well as the spacer thickness are parameters allowing to manage the spectral positions of excitations, their overlapping and interactions in such metal-dielectric-metal (MIM) systems over a wide spectral range. This allows for engineering the desired behavior and response of such MIM structures. However, electron beam lithography is usually used for the preparation of ordered plasmonic nanostructures, which restricts the size of the lattices to few tens of microns in most cases. Therefore, the investigation of such structures demands devices with high spatial resolution of devices applied for. A Patent-Pending, home-build fast ellipsometer with spatial resolution of only few microns was used in our investigations. Spectra of ellipsometric angle "psi" clearly displays distinct features, which can be prescribed to the Bragg mode of the lattice, a dispersionless mode coupled with the plasmonic layer that manifests in a wave-like structure and areas where possibly, coupled modes split. More detailed analysis as well as investigation of the influence of different system dimensions will be discussed in this contribution.

Resume : Self-assembled phthalocyanines (Pcs) monolayers have been studied with scanning tunnelling microscopy (STM) due to the organized 2D arrays that they form with potential applications in functional organic devices. The metal central region gives them important electronic, optical and optoelectronic properties and the possibility to extend the 2D monolayer into three dimensions through vertical reaction chemistry [1,2]. Synthetized metal Pcs [3,4] were assembled in graphite and followed by STM. High resolution images were obtained during the formation of the monolayer using a method previously applied in porphyrin monolayers [1,2,5,6]. The molecules were added to graphite trough an interface with tetradecane and the monolayer formation was followed in real time using molecular resolution images obtained by STM. Differential functional theory simulations were made to support the STM results. . [1] Q. Ferreira et al, J. Phys. Chem C, 2014 [2] Q. Ferreira et al, Nanot., 2011 [3] A. Sastre et al, Sust. Energy Fuels, 2017 [4] A. Sastre et al, J. Phys. Chem. C, 2016 [5] Q. Ferreira et al, Applied Surface Science, 273, 220, 2013 [6] Q. Ferreira et al, J. of Microscopy, 2018 Acknowledgements We thank FCT-Portugal, under the project UID/EEA/50008/2013 for financial support

Resume : The aim of this work is fabrication of PEDOT-PSS polymer composites reinforced with single-walled and multi-walled carbon nanotubes and their electrical investigation on the temperature range of 50-200 K. Hybrid composite films were prepared starting from 1% water suspension of poly-3,4,-ethyldioxitiophen from Sigma Aldrich (USA) stabilized with surface active anion substance (polystyrene sulfonic acid). Two types of nanofiller were used: purified (90 wt%) single-walled carbon nanotubes (SWCNTs) with average diameter of 1 nm and lengths within the range of 5 to 30 µm and purified multiwalled carbon nanotubes (95 wt%) with average outside diameter of 65 nm, average inside diameter of 10 nm and lengths within 10-20 µm (MWCNTs). Both SWCNTs and MWNTs were supplied by US Research Nanomaterials. Electrical tests were carried out exploiting E7-20 RLC Meter capable of measuring impedances in the range of 10?5 to 109 Ohms using 1 V excitation signal from 40 mV to 1 V at frequencies ranging from 25 Hz up to 1 MHz. Temperature experiments were performed utilizing custom cryostat equipped with a DE-202A closed cycle cryocooler (Advanced Research Systems). Temperature control functions were performed by Cryocon 32 (Cryogenic Control Systems Inc.) temperature regulator. It is established that composite films with multi-walled nanotubes loading show lower resistances as compared to their single-walled counterpart.

Resume : Recent studies have shown the feasibility of developing direct current (dc) driven III-nitride deep ultra-violet (UV) photonic devices through band gap engineering of epitaxially grown hetero-structures. Alternatively, one can consider developing deep ultraviolet (UV-C) light sources operating on the principles of hot electron impact excitation processes in a boron nitride (BN) phosphor. It was shown that high quality BN nanosheets (BNNSs) generate excitonic emission at 225 nm under electron excitation and thus can be considered for developing alternating current driven thick electroluminescence (ACTEL) devices. In this work we have explored experimentally and theoretically, BN wide band gap semiconductor for achieving deep UV-C emission under energetic electron excitation. Temporal and spatial cathodoluminescence (CL) of BN materials having different morphologies (i.e. nano-sheets, nano-rods and nano-particles) synthesized by physical or chemical methods were explored for deep UV-C generation. It was found that CL of the BNNSs synthesized by pulse laser-deposition generate the strongest free exciton emission at 215 nm. Next, a theoretical approach based on the Bringuier model for generating luminescence in the UV-C region from hexagonal BNNS (h-BNNS) through impact excitation under a high electric field was explored. We have also considered the theoretical efficiency of electroluminescence (EL) in h-BNNS phosphor used for an ACTEL device by using the impact excitation rate theory developed for II-VI devices. Finally, we have simulated the deep UV-C ACTEL device?s efficiency by considering different active h-BNNS layer thickness and the applied electric field in order to optimize the luminescence yield.

Resume : Selective growth of inorganic materials in one of the domains of block?copolymer (BCP) thin films can be used for enhancing polymer etch resistance for pattern transfer to the substrate. Selective sequential infiltration synthesis (SIS) of self-assembled PS-b-PMMA thin films has been proposed to convert PMMA nanostructures in inorganic Al2O3 using trimethylaluminum (TMA) in combination with H2O as precursors. Perpendicular orientation of the nanodomains with respect to the substrate in PS-b-PMMA films requires the introduction of a grafted random copolymer (RCP) film with tailored composition to neutralize the preferential wettability of PS with respect to the PMMA on the SiO2 surface. However, the RCP film contains MMA monomeric units and consequently is infiltrated during SIS process, with the formation of an Al2O3 continuous layer at the interface between the BCP film and the substrate. A breakthrough process with a specific dry etching chemistry is required to remove this layer a nd expose the Si substrate. Therefore, detailed knowledge of the infiltration process in this RCP layer is mandatory for the effective exploitation of the infiltrated Al2O3 nanostructures as hard mask for lithographic applications. In this work, we present a detailed investigation of the infiltration of Al2O3 in P(S-r-MMA) thin films with thickness ranging from 8 to 100 nm and variable styrene content ranging from 0 to 100% by means of in situ and ex-situ analysis.

Resume : Block copolymer (BCP) self-assembly (SA) leading to thin films with periodic ordered nanostructures featuring different morphologies has been exploited in a number of technological applications. Among them, polydimethylsiloxane (PDMS) containing BCPs have attracted a great interest because of the possibility to generate high-resolution nanostructures with dimension below 10 nm. The SA of the PDMS-containing BCPs in periodic nanostructures can be achieved by different approaches, but thermal annealing would be highly desirable for easy integration in a product process flow. In this work, we report a systematic study on the SA kinetic and morphological evolution of a cylinder-forming polystyrene-block-poly(dimethylsiloxane-random-vinylmethylsiloxane) PS-b-P(DMS-r-VMS) thin film (Mn = 22 kg/mol). BCP films were deposited on PS or PMMA brushes by spin casting from various solvents. A simple thermal treatment at high temperature was used to promote the formation of PDMS cylinders embedded in a PS matrix and parallel oriented with respect to the substrate. Grain coarsening kinetic of the system was studied considering the time evolution of correlation lenght (L). In most of the cases a power law dependence of L ~ t^G with G = 0.21 was obtained irrespective of the combination of brush layer and solvent. For some specific combinations, conversion from parallel cylinders to dots was observed highlighting the important role of residual solvent on the SA process.

Resume : Challenges for sub-10 nm patterning can be addressed by the direct self-assembling of block copolymers (BCP) in combination with a volume selective sequential infiltration synthesis (SIS). Selective growth of inorganic materials in one of the BCP domains can be used for enhancing polymer etch resistance for pattern transfer to the substrate. In order to get a deeper understanding of the SIS process, we investigated the infiltration of trimethylaluminum (TMA) in combination with H2O for the synthesis of Al2O3 into polymethylmethacrylate (PMMA) and polysterene (PS) films by means of dynamic in situ spectroscopic ellipsometry. Swelling of the polymer films is probed during SIS cycle, and observed to be affected by SIS process parameters as TMA dosing and purging. PS film swelling is almost negligible during TMA exposure reflecting the inertness of PS to TMA molecules. However upon several SIS cycle process, progressive swelling is observed and some Al2O3 growth is observed also in PS films. This is attributed to defects in the film, leading to loss of infiltration selectivity. Conversely significant swelling is observed in PMMA films during TMA exposure. Investigating the swelling of fresh PMMA films during TMA infiltration at 90°C, the diffusion coefficient of TMA in PMMA was extracted and shown to be dependent on polymer molecular weight but not on the film thickness, indicating a Fickian behavior for diffusion of TMA in PMMA films.

Resume : Protein phosphorylation investigation currently represents an important field of method development. Direct analysis of phosphopeptides in a complex mixture is not feasible, due to the low abundance of phosphopeptides and the suppression caused by the more abundant non-phosphorylated peptides during the MS analysis. Accordingly suitable enrichment and selective systems is highly required. In this frame, IMAC (Immobilized Metal Affinity Chromatography) still represents the most frequently used technique to enrich phosphopeptides. Positively charged metal ions can be immobilized by different chelators, such as the traditional chelating agents nitrilotriacetic acid and iminodiacetic acid (IDA), among others. In this context, a new functional multishell magnetic material for IMAC enrichment of phosphopeptides was produced by a multistep procedure (Fig. 1) employing the ?grafting from? approach by the activator regenerated by electron transfer?atom transfer radical polymerization (ARGET-ATRP) technique, to obtain Fe3O4@silica@GMA nanoparticles. The prepared material was extensively characterized both from the structural point of view by SEM analysis and for the compositional point of view by thermogravimetry alone and coupled with a gas chromatographic separation and a mass spectrometric detection (TGA-GC-MS). Classical techniques require the detachment from the substrate of the organic part causing major structural modifications. On the contrary, by TGA-GC-MS each step of the organic decoration of the silica particles was characterized directly on the sample without any pre-treatment of detachment from the substrate. Fe3O4@silica@GMA nanoparticles were successfully tested for the enrichment of a bovine serum albumin in mixture with casein.

Resume : Hydroxyl-terminated P(S-r-MMA) random copolymers with molecular weight ranging from 1.7 to 69 kg/mol and a styrene unit fraction of 61% were grafted onto a silicon oxide surface and subsequently used to study the orientation of domains with respect to the substrate, in cylinder-forming PS-b-PMMA block copolymer thin films. When the thickness (H) of the grafted layer
is greater than 5−6 nm, a perpendicular orientation is always
observed because of the efficient decoupling of the BCP film
from the polar SiO2 surface. Conversely, if H is less than 5 nm,
the critical thickness of the grafted layer, which allows the
neutralization of the substrate and promotion of the
perpendicular orientation of the nanodomains in the BCP film, is found to depend on the Mn of the RCP. In particular, the critical thickness necessary to promote the perpendicular orientation of the cylinders in the BCP thin film changes as a function of the molecular weight of the RCP. An effective neutralization is observed for a specific Mn value when thickness nears 2Rg. For this thickness value, the configuration of the grafted RCP molecules closely resembles the random coil and the diffusion of the BCP into the grafted layer is counteracted by the entropy loss associated with the stretching of the grafted chains necessary to accommodate the BCP molecules. Within this regime, 2 nm thick films of RCPs with an Mn of 1700 (2Rg = 2.1 nm) are sufficient to promote the perpendicular orientation of the PMMA cylinders in the PS-b -PMMA BCP film. From a technological point of view, minimization of the thickness of the RCP allows optimization of pattern transfer fidelity.

Resume : Boron-terminated polystyrene with molecular weight ranging from 1800 to 18000 g/mol were synthesized for p-type doping of silicon substrates through spin-on technique. Several polymers were prepared using the ARGET-ATRP method using tert-butyl 2-bromoisobutyrate as initiator, changing monomer to initiator ratio and the reaction time. After polymerization, polystyrene samples were functionalized in order to end-cap the chains with a boron-containing molecule. Various polymers were characterized by SEC, to estimate Mn, Mw and PDI, by NMR (1H and 13C) in order to investigate the correct structure of the molecules and by TGA-GC-MS for knowing the thermal behavior and the amount of boron into the polymers.

Resume : The aim of this work is to obtain block copolymer brushes by a combined grafting to and grafting from approach. A new strategy was employed in which the second block re-growths starting from a homopolymer brush layer obtained by the grafting to approach. In detail, polystyrene samples with molecular weight ranging from 2.5 to 13 kg/mol and narrow molar mass distribution were synthesized by nitroxide-mediated-polymerization (NMP) using N-tert-butyl-N-[1-diethylphosphono(2,2-dimetylpropyl)] nitroxide (SG1/DEPN) as polymerization controller. Such polymers were grafted onto a silicon oxide surface by Rapid Thermal Processing (RTP) at different temperatures. As thermolabile groups deriving from the terminal SG1 are located at the silica surface, they could allow a synthesis of block copolymers via the grafting from approach by surface initiated NMP. Preliminary experiments of regrowth from surface were conducted with deuterated styrene and 4-vinylpyridine. The corresponding block copolymer brushes were obtained and their characteristics discussed as a function of the relevant reaction parameter.

Resume : The grain coarsening process in thin films of strongly segregated cylinder forming PS-b-PMMA BCP with degree of polymerization, N, ranging from 461 to 1281 (molecular weight: Mn = 48-132 kg/mol) was accomplished by fine-tuning of the annealing temperature (TANN = 160-290 °C) and time (tANN = 1-900 s) in a rapid thermal processing machine. Hexagonally packed PMMA cylinders perpendicularly oriented with respect to the substrate with different characteristic dimension were obtained. These PS-b-PMMA thin films can be described in the framework of the strong segregation limit. The evaluation of the correlation length allows determining the growth exponent  and the activation enthalpy HA for each N. For the lowest N,  saturates at ~ 1/3. This value equals that of systems that coarsen with a diffusion-limited mechanism. Increasing XN, both  and HA decrease following an exponential decay as a function of N with exponent ~ XS-MMA. This dependence exactly mimics that of the chain diffusivity. In recent data on weakly segregated cylinder forming PS-b-PMMA BCP with N = 379 (Mn = 39 kg/mol), the values of correlation length progressively increase with time following a power law with  ~ 1/2 suggesting that a curvature limited mechanism of the lateral ordering process. Interestingly the value of the activation enthalpy HA continues to follow the exponential evolution as a function of N with exponent ~ XS-MMA that was observed in the case of strongly segregated cylinder forming PS-b-PMMA BCP thin films.

Resume : The capability to control dopant incorporation within semiconductor materials with atomic accuracy represents a major challenge toward further scaling of electronic devices. A promising strategy is the monolayer doping (MLD), which consists in the creation of a well-ordered monolayer of dopant-containing molecules bonded to the surface of the substrate. In this work, we extended this approach by studying the self-assembly of phosphorous-containing end-functional polymers. Monodisperse polystyrene and poly(methyl methacrylate) polymers with different molar masses, end-terminated with a phosphate containing moiety were prepared. These polymers were grafted to an activated silica surface by thermal annealing in a Rapid Thermal Processing apparatus. Subsequent removal of the organic layer by oxygen plasma and capping with SiO2 leads to the formation of a P δ-layer embedded in a SiO2 matrix. Taking advantage of the self-limiting nature of the “grafting to” process, precise control of the areal dose and spatial distribution of dopants can be achieved by tuning the polymer molar mass. Repeated cycles of polymer grafting followed by plasma hashing led to a stepwise increase in the dose of P atoms grafted to the silica surface. P injection in the silicon substrate was promoted by high temperature thermal treatments. Finally, the combination of this approach with block copolymer lithography allows to control at the nanoscale the lateral confinement of the dopant atoms.

Resume : Copper (Cu) is used in non-enzymatic systems due to its excellent selectivity and organic molecules oxidative capacity, for this reason its use for the cholesterol oxidation is considered. Therefore, in this work we present the optimization of synthesis Cu nanoparticle, presented by Maya et al for to reduce their size nanoparticles as a principal objective. In these sense, the particle size obtained was characterized by dynamic light scattering (DLS), while the morphology by the scanning electron microscope (SEM). For another hand, the composition by energy dispersive spectroscopy X-ray (EDS) and X-rays photoelectrons emitted spectroscopy by (XPS), crystallographic analysis by transmission electron microscopy (TEM). The electrochemical response of the Cu-NPs was examined using cyclic voltammetry. The physicochemical characterization demonstrated a particle size reduction of 98%, indicating an excellent process optimization for reduce de nanoparticles size. Additional, this optimization did not significantly alter the crystallographic properties of the material. Through the corresponding analyzes, it was observed that the material is composed of 79% metallic Cu, while only 21% is carried to copper oxides. On the other hand, the electrochemical response indicates an excellent performance of Cu-NPs in basic medium. In addition, according the results, the Cu-NPs synthetized have an excellent catalytic response in the cholesterol presence, which, it is possible to appreciate from the first cholesterol addition (0.1 mM). Therefore, the material synthesized in this work is possible to be used in systems such as an electrochemical sensor or for use in energy generation systems as fuel microcells.

Resume : Core shell nanoparticles comprise of two or more materials, such as metals and biomolecules, wherein one of them forms the core at the centre, while the other material/ materials that were located around the central core develops a shell. The plant mediated has become an emerging field of sustainable nanotechnology. Though several biological resources have been exploited for the synthesis of core-shell nanoparticles, but plant based materials appear to be ideal candidates for large scale green synthesis of core-shell nanoparticles. In our study we have used Fresh leaf extract of Gracinia cambogia Linn. as the reducing and capping agent for the synthesis of ZnO:Ag core shell nanoparticles. UV-Visible spectroscopy confirmed the formation of ZnO:Ag NPs as the absorbance peak was found at 267 nm and the SPR band at 410 nm corresponding to Ag shell structure. This was reconfirmed by the XPS analysis. The two peaks at binding energies of 1021.6 eV and 1044.6 eV in the XPS spectra of Zn 2p correspond to the Zn 2 2p 3/2 and Zn 2 2p 1/2 , respectively. The presence of binding energies peaks at 367.6 eV corresponds to Ag 3d5/2 and 531.6 eV corresponds to oxygen O1s.

Resume : Today, temperature regulation at the macro and microscale is one of the major contributors to the energy demand of our society [1]. Indeed, modern cooling systems account for 15% of the global energy consumption and 10% of the greenhouse gas emissions. Furthermore, a tenfold growth in the demand of cooling technologies is expected in the next 30 years, mainly due to global warming [2]. In this work, a self-assembled opal-based thermal blackbody is proposed to achieve improved thermal performance of devices that undergo critical heating during operation. The working principle of the cooling device is based on the interaction of the transverse optical phonons and equally polarized electromagnetic waves, which results in an intense evanescent field confined at the surface of a polar-dielectric interface, the so called surface phonon polariton (SPhP). Such surface excitations have the ability to enhance thermal energy conduction [3], [4] and, in the presence of a grating, they can be diffracted as infrared thermal energy. Using these two concepts we demonstrate experimentally radiative cooling of a surface with a cooling power of 21W/m2. The monolayer opal emits longwave infrared radiation through the atmospheric window and in a large range of wavelengths, thus providing effective radiative cooling by using the outer space at 3K as a heat sink. A significant temperature decrease of a hot surface is achieved using the proposed radiative cooler. [1] Y. Joshi and P. Kumar, Energy efficient thermal management of data centers. New York: Springer Science & Business Media, 2012. [2] E. A. Goldstein, A. P. Raman, and S. Fan, ?Sub-ambient non-evaporative fluid cooling with the sky?, Nat. Energy, vol. 2, p. 17143, Sep. 2017. [3] Chen, D.-Z. A., Narayanaswamy, A. & Chen, G. Enhancement of in-plane thermal conductivity of thin films via surface phonon-polaritons. ASME 2005 Int. Mech. Eng. Congr. Expo. 1, 841?846 (2005). [4] Tervo, E. J., Adewuyi, O. S., Hammonds, J. S. & Cola, B. A. High thermal conductivity in polaritonic SiO 2 nanoparticle beds. Mater. Horiz. 3, 434?441 (2016).

Resume : Organic molecules can self-assemble into diverse aggregate morphologies like nonotubes, nanowires and nonoribbons, depending on the molecular interactions such as amphiphilic, hydrogen bonding, van der Waals forces, and π-π stacking. Also molecular shape and other conditions are paying role as well. We show that quite conventional mesogenic molecules (rod-like or bent-core) my form nanotubes or nanoribbons. We will discuss the chiral segregation effect, origin of optical activity for these materials and the shape transition induced by additives that adsorb to the membranes forming the nano-objects.

Resume : Tin sulfide (SnS) thin films were obtained by chemical bath deposition by using two surfactants: anionic sodium dodecylsulfate (SDS) and cationic Benzethonium chloride. The influence of the surfactants on the thin films properties was investigated and was correlated with their photocatalytic efficiency for methylene blue (MB) dye degradation under sun light irradiation. The structural, morphological, chemical composition and optical properties of samples were analyzed by using XRD, MEB, EDX and spectrophotometer. The results indicate the use of SDS gives thin films with higher photocatalytic activity compared to SnS free SDS surfactant. In fact, SnS grown with SDS surfactant has a dye degradation of nearly 88% during 4h exposition to sun light. Whereas SnS film degrades only 65% of dye molecules in the same time interval. Key words SnS, CBD, thin film, surfactant, photocatalytic activity

Resume : The indium doped lead sulfide (In:PbS) thin films were synthesized by the simple chemical bath deposition (CBD) method and the photovoltaic performances of In doped PbS derived absorber layers are studied. All the films are polycrystalline in nature with face centered cubic structure. The doping of In significantly altered the morphology of PbS from pyramidal to quadratic shape by the arrangement of small nanoparticles. A change in preferential orientation from the (111) direction to the (200) direction as well as surface smoothing and roughness decreasing of the films were observed with In content. The layers grown with (2 at%) In content had a strong (200) preferred orientation, well-defined quadratic grain shapes, minimal resistivity of 0.76×10-1 Ωcm with an optical energy band gap (Eg) of 1.45 eV. Using the optimised conditions, we used 2 at% In:PbS as an active layer in FTO/Sn:ZnO/In:PbS/Al solar cell structure with conversion efficiency of 1.02%. As an added advantage of the low band gap PbS (Eg = 0.72 eV) stacked over a wide gap 2 at% In:PbS (FTO/Sn:ZnO/In:PbS/PbS/Al), the device operate as a solar cell robustly with power conversion efficiency of 2.65%. Keywords: Chemical bath deposition; PbS thin films; In3+ content; Preferential orientation; Optoelectronic properties; Solar cells

Resume : Iron oxide (Fe2O3) thin films were deposited on ordinary glass substrate by chemical spray pyrolysis technique with different volumes (V= 50, 75, 100 and 125 ml). Structural and optical properties were studied by X-ray diffraction and spectrophotometer. The XRD analysis of the layers showed that they were α-Fe2O3with (104) as a prefferred orientation. A degradation of crystallinity followed by a change in plan orientation from (104) to (110) was observed when sprayed solution volume rised to 125 ml. The best cristallinity is obtained for V = 100 ml. In fact, the dislocation density seems to be reduced to the value 0.65x 1014 lines. m-2. The optical study revealed that for all volumes the as deposited films absorbed the UV and most of the visible. Fe2O3 thin films displayed an average band gap around 2.15 eV for direct transition and 2 eV for indirect transition. Moreover, the obtained measurement result of gas sensing prove that α-Fe2O3 thin film based sensor is very promising semi-conductor for fabricating gas sensor with great performance thanks to its good sensitivity and stabilityeven at an ethanol gas concentration of 5 ppm. Key words:Chemical spray pyrolysis, Iron oxide, Structural and optical properties, Gas sensor.

Resume : Mixed oxides (ZnO, SnO2) thin films were prepared by spray pyrolysis method on glass substrates by spray pyrolysis technique. The mixed oxides were prepared in the range of 25 at.% to 60 at.% by altering the Zn/(Sn+Zn) atomic ratio in the starting solution. The structural, morphological and optical properties of the grow films were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) analysis, atomic force microscopy (AFM) and spectrophotometry. XRD analysis indicate the coexistence of both tetragonal casseterite structure of SnO2 and hexagonal wurtzite phase of ZnO for all mixed thins films. Microstructural parameters such as micro-strain and crystallite size suggest the good crystallinity of mixed thin film at 60 at.%. Optical analysis by means of transmittance T ( and reflectance R ( measurements allowed us to determine the optical constants for single and mixed oxides. High average transmittance and low reflectance properties make the films good materials for anti-reflection coatings and for solar thermal applications in flat-plate collectors, etc. Keywords: Zinc oxide; Tin oxide; Mixed oxides; Spray pyrolysis; Optical properties.

Resume : The MgO magnesium oxide thin films are synthesized by the chemical spraying technique "SPRAY" using different precursors of magnesium with 0.2M concentration and the bi-distilled water as the solvent. Structural, optical and morphological analysis are performed by XRD, FTIR, spectrophotometry and AFM. They respectively confirm the crystallization of magnesium oxide in the CFC cubic face-centered structure and his gap energy is of the order of magnitude 4 eV. Under solar irradiation, these layers have a photocatalytic activity: the absorbance of methylene blue is observed for the wavelength 665 nm, which corresponds to the total degradation of methylene blue dye. Keywords:Thin films, Magnesium oxide, Photocatalysis

Resume : Multi-layers Cu2FeSnS4 (CFTS) thin films were elaborated by spray pyrolysis technique on glass substrates by different deposition runs (1, 2, 3 and 4) using methanolic solution. Structural and optical properties of each run were investigated respectively by X-ray diffraction and spectrophotometer in the wavelength range of [250–2500] nm. All runs show that Cu2FeSnS4 thin films are preferentially oriented along (112) plan located at 2θ=28,61°. The good crystalline quality with narrowest diffraction peak and highest grain size has been obtained after three deposition runs. Optical transmission and reflectance have revealed that after three deposition runs, band gap energy is about 1,48 eV and the absorption coefficient is equal to 9,6 104 cm-1 which is considered as the best values compared to other runs. Refractive index (n), extinction coefficient (k), the real (ε1) and imaginary (ε2) parts of the dielectric constant were also determined. These experimental results have shown that optimum multi-layer CFTS thin film is obtained at three deposition runs. All obtained results permit to use CFTS material as an absorber layer in solar cell devices. Keywords: CFTS, Spray pyrolysis, multi-layers, structural, optical propertie; solar cells.

Resume : Detection of bacteria is important aspect of science and goal of numerous studies. Bacterial infections concerns many fields, such as hospital care (90 000 deaths during hospitalization every year) or food industry (76 million illnesses annually). There is a constant need of development of new sensors for fast and sensitive bacteria detection. One of the envisioned design is based on bacteriophages – viruses that infect bacteria. Despite some attempts in the field of phage-based sensors, sensitivity and repeatability issues still need to be addressed. Main goal of presented research was to create fast, sensitive and reliable sensor for bacteria detection based on bacteriophages. Only specific orientation of phages allows for effective bacteria capture. Ordered layers of bacteriophages properly oriented in the electric field were able to detect bacteria in a fast and efficient way. Application of constant electric field enabled to partially orient phages and resulted in 4 times higher sensitivity. In further research, we utilized alternating electric field. Second approach combined with chemical modification allowed for 64-fold increase in sensitivity and a limit of detection as low as 100 bacteria/ml. Properties, such as density of phages, selectivity and response in real samples, were analyzed and well characterized. Obtained sensing elements can be applied for selective, sensitive, and fast (15 min) bacteria detection.

Resume : We design and experimentally investigate an artificial sheet material fabricated by electron beam lithography, subsequent deposition of 30 nm gold and lift-off procedure. This so called plasmonic metasurface is able to work as a lens for imaging on very small length scales with simultaneous frequency conversion for the incident near-infrared light. With our approach, we take advantage of the nonlinear geometric phase originating from the arrangement of plasmonic nanostructures with specific rotational symmetry. Depending on the incident circular polarization of light, the phase profile for the nonlinear harmonic generation process can be switched between convex and concave. In our experiments, we determine the formation of real and virtual focal planes for illumination with femtosecond laser pulses and we demonstrate nonlinear imaging abilities that give rise to real and virtual images of real objects at visible wavelengths. These considerations are expanded on nonlinear dielectric metasurfaces with higher efficiencies. Therefore, imaging with even higher harmonic generation processes can be obtained and most importantly, we found that the nonlinear image evolution is not governed by the traditional lens equation but by a generalized version of it. This work paves new ways for nonlinear metasurface devices in the field of nano-optoelectronics or quantum communication technologies.

Resume : In optomechanical systems, co-localizing light and mechanical oscillations at the nanoscale can lead to strong interaction between photons and phonons. Such optomechanical coupling enables on the one hand extremely sensitive detection of nanoscale motion, that allow exploring the fundamentals of quantum measurement as well as novel sensing technologies. On the other hand, it leads to large optical forces that allow new ways to control mechanical motion and transport. We study sliced photonic crystal nanobeam systems in which photons and phonons are coupled with extreme strength. We demonstrate sensitive optical displacement detection in such systems. Owing to the large optomechanical coupling strength, these measurements can be both strongly nonlinear and fast - i.e. reaching near-quantum-level precision within times much shorter than a mechanical period. This provides new paths to evading the standard quantum limit and creating and characterizing nonclassical states of motion through measurement. Moreover, we show that the optical forces in such systems can mediate phononic signal transport between different nanomechanical modes. We show that light can imprint an effective gauge field on such transport, mimicking the Aharonov-Bohm effect with sound. This can be used to create topologically protected states in nanomechanical systems.

Resume : Most vivid colours in nature originate from the interference of light with nanostructured materials. In many cases, the nanostructure is not perfect and introducing disorder results in additional optical effects that might change the reflection properties. Our current research is broadly focused on two questions: (i) how are optical properties influenced by disorder? and (ii) can we replicate natural photonic structures with a controlled degree of disorder? For this, we systematically investigate the colour change of distributed Bragg reflectors in relation to its key parameters, i.e. the total numbers of layers, the refractive index contrast and their thickness. Here, we have manufactured distributed Bragg reflectors (DBRs) using different techniques. Using spin coating, we deposit several layers of alternating porous materials where each layer has a controlled thickness and refractive index. We show that a reflector constructed of three repeating series of six layers gives optical properties that are a result of the disorder. In this case, the disorder is not fully random, but small deviations in the structure have a large influence on the colour and still produce a narrowband response. Alternatively, we show a different proof-of-concept solution using lithographically produced multi-layered patterns that readily assemble into a variety of Bragg reflectors with a different number of layers. We discuss the influence of disorder and the use of these materials in novel optical applications.

Resume : Optomechanical structures are potential building blocks for phononic circuits and quantum computing, and a huge focus is put on non-linear applications due to several potentially huge impact features such as phonon lasing, chaos and high sensitivity readout. Phononic circuits, in which the information is carried by phonons, will require a complete set of components. Optomechanical structures can already be used to create coherent phonon sources and detectors, and recently a phonon memory has been achieved. However, other functions, especially more complex, remain challenging. Here, we use our silicon optomechanical cavities displaying phonon lasing to propose and demonstrate a way to modulate the coherent phonon emission properties by photothermal effect induced by an external laser. Thus, we effectively create a phonon switch working at ambient conditions of pressure and temperature with a switching power as low as 130 μW. The working speed of our switch is only limited by the build-up time of the mechanical motion of the optomechanical structure and solving the equations of the system shows good agreement with our experimental results. We additionally demonstrate other modulation schemes in which the coherent emission is maintained, including harmonics modulation, where different harmonics of the optical force are used, and modulation to- and from a chaotic regime. Furthermore, with this scheme we are able to selectively modulate the emission of any single cavity without affecting its surroundings, which is an important step towards future circuits with networks of optomechanical phonon emitters.

Resume : Optical metamaterials are artificially structured materials whose interaction with light is determined by their structure rather than by their chemical composition. Their fabrication remains technologically challenging, as it requires structures with nanoscale features over macroscopic areas. Such a structure would be prohibitively expensive to fabricate by top-down lithographic processes. Alternatively, 3D optical metamaterials can be fabricated from the bottom up by replicating continuous network structures of self-assembled block copolymers. Creating the desired functionality in “self-assembled” optical metamaterials requires precise three-dimensional structural control of the polymer template used for their fabrication. In this talk, we will present recent results showing that polymer films with well-ordered structures in three dimensions can be generated by controlled solvent vapor annealing in combination with in situ structural characterization by means of x-ray scattering. We show that using these templates 3D optical metamaterials with interesting optical properties can be fabricated by electrodeposition of plasmonic metals into voided polymer templates.

Resume : Scanning X-ray nanodiffraction is an excellent tool for materials science related in situ studies. It readily serves structural information with sub-µm spatial resolution from crystalline and semi-crystalline materials (metals, biomaterials, synthetic compounds). That way grain orientation, residual stress profiles, crystal structure or texture can be obtained in a non-destructive analysis. Because of the long focal distance focusing, the wide X-ray energy range and a flexible sample positioning system, high resolution nanodiffraction experiments can be performed even under demanding conditions e.g. on strongly absorbing metallic samples or in extended sample environments. The Nanofocus Endstation of beamline P03 (PETRA III, Hamburg) is part of the German Engineering Materials Science Center (GEMS) and is operated jointly by Helmholtz-Zentrum Geesthacht and the University of Kiel. 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 sub-micron sized, hard X-ray beam. The strong focus on materials science at P03 is demonstrated by the wide range of experiments already performed with in situ sample environments: pressure, indentation force, tensile stress, fluid shear, magnetic fields - all of these parameters were successfully modified in situ and combined with the high spatial resolution provided by nanofocused beam. This contribution will provide a comprehensive introduction to the experimental facilities at P03 and showcase a compilation of past experiments where in situ applications have been combined with X-ray nanodiffraction.

Resume : As novel nanomaterial devices, e.g. semiconductors, energy related-, electronic or optical components become increasingly smaller, the need to study the properties of their layers and interfaces at the nanometer scale increase. Proven methods of characterisation must be used in order to understand how atoms are arranged within ultra-thin-nano and/or multilayered films or structures, how structures are assembled and interconnect, as how they are evolving with time. Indeed, the characteristics of such devices, and their related performance are often influenced by layer parameters such as film thickness, density or surface/interface roughness and elemental impurities. X-ray techniques conducted in grazing incidence conditions allows to probe large areas, and thus to extrapolate accurately the device performance and characteristics. By combining angularly resolved Grazing Incidence X-ray fluorescence spectroscopy (GIXRF) and X-ray reflectivity (XRR), one has access to the sample’s depth composition, given by the angularly resolved fluorescence contributions of the materials’ elements and to its optical parameters, respectively. A quantitative analysis is obtained after fitting a theoretical curve to as measurement by refining the parameters to reconstruct appropriately the structure. We will illustrate the potential of these techniques in the metrology of devices of industrial relevance such as optical components, opto-electronics and semiconductor devices, and nanoparticles.

Resume : In most cases, bulk-type reference-materials do not provide optimal calibration schemes for the analysis of nanomaterials as e.g. surface and interface contributions may differ from bulk. Also, spatial inhomogeneities may exist at the nanoscale or the response of the analytical method may not be linear when going from bulk to the nanoscale. Thus, the availability of suited nanoscale reference materials is drastically lower than the current demand. The reference-free X-ray fluorescence (XRF) technique of PTB can address this disparity as it enables an SI traceable quantitative characterization of nanomaterials without the need for reference or calibration standards. This opens a route for the XRF based qualification of calibration samples. As a first example, we use physical vapor deposition techniques for the development of layer-like reference samples with very low mass depositions. Different reference samples were fabricated for application in XRF and total-reflection XRF analysis. They were quantitatively characterized using synchrotron radiation employing PTB´s reference-free XRF approach. In a second example, we work on the development of nanostructures as calibration samples. Several lithographic 2D and 3D nanostructures have been fabricated at PTB using e-beam lithography and were characterized using the reference-free grazing incidence XRF methodology of PTB. Here, an advanced and novel calculation scheme for the intensity distributions within the X-ray standing wave field (XSW) is required. In addition to the traceable quantification of elemental mass depositions, this allows for a determination of in-depth elemental distributions and the dimensional properties of the nanostructures.

Resume : The sequential infiltration synthesis (SIS) process, which is derived from atomic layer deposition (ALD), is based on the cyclic infiltration of a polymer with inorganic materials through sequential and self-limiting exposures to gas-phase. SIS is often used to harden lithographic resists [1], to produce inorganic nanostructures within block copolymer (BCP) templates [2] or to obtain conformal coatings with low refractive indexes [3]. Despite the development of a large number of applications, the mechanism behind this synthesis process is still incomplete [4]. The most studied inorganic oxide in ALD is Al2O3 which can be grown by cyclic reactions of trimethyl-aluminum (TMA) and water precursors. The TMA has been demonstrated to react preferentially with PMMA in PS-b-PMMA BCP systems. However the role of polystyrene (PS) as a diffusion channel for the gaseous precursor is still discussed. A better understanding of this mechanism can be achieved by means of grazing incidence X-ray fluorescence (GIXRF) analysis that can address the open questions regarding the infiltration mechanism through a depth-dependent determination of the infiltrated oxide in the polymer matrix. The X-ray standing wave (XSW) field, arising at the flat sample surface, presents in-depth intensity variations occurring with angular dependence. Such field is modeled to obtain information on the infiltration profile inside the polymer. Moreover, the employment of calibrated instrumentation allows for reference-free GIXRF [5,6] and thus for a quantification of the elemental mass deposition of the inorganic material. GIXRF analysis was performed on PMMA, PS-r-PMMA and PS-b-PMMA layers treated with 1 to 10 cycles of Al2O3 ALD using TMA and H2O precursors. Si/SiO2 substrates were treated in the same conditions and used as a reference for the quantitative determination of the Al2O3 growth rate. The non-destructive analytical technique allows to discern the difference in the infiltration process between PS and PMMA. [1] Y. C. Tseng, et al., J. Mater. Chem, 21, 2011, 11722. [2] J. Kamcev, et al., ACS Nano, 7, 2012, 339. [3] D. Berman, et al., ACS Nano, 11 (3), 2017, 2521. [4] M. Biswas, et al., J. Phys. Chem. C, 119, 2015, 14585. [5] P. Hönicke, et al., Phys. Status Solidi A, 212 (3), 2015, 523. [6] M. Müller, et al., Materials, 7(4), 2014, 3147.

Resume : Polarity is known to affect the growth and properties of ZnO single crystals and films [1], but its effects are mostly unknown in nanorods (NRs). While ZnO NRs grown by vapor phase techniques are Zn-polar, they can be of either O- or Zn-polarity when grown by chemical bath deposition [2]. In this context, we address the issue of the polarity-dependent growth and properties of ZnO NRs following the selective area growth using electron beam lithography [3,4]. To leave polarity as the only varying parameter, well-ordered O- and Zn-polar ZnO NR arrays with high structural uniformity are grown by CBD under identical conditions. Zn-polar ZnO NRs are found to exhibit larger growth rates than O-polar ZnO NRs [3]. This is explained in the framework of the surface reaction- / diffusive transport-limited elongation regime analysis. Four-point probe resistivity measurements in metal contact and multi-probe scanning tunneling microscopy configurations show the high electrical conductivity of O- and Zn-polar ZnO NRs as well as its polarity dependence [4]. This is attributed to the massive incorporation of hydrogen as shown by Raman scattering and cathodoluminescence. These findings show the relevance of considering polarity as an important quantity to be controlled for nanoscale devices. [1] J. Zúñiga-Pérez, V. Consonni et al., Applied Physics Reviews 3, 041303 (2016). [2] V. Consonni et al., ACS Nano 8, 4761 (2014). [3] T. Cossuet et al., Langmuir 33, 6269 (2017). [4] T.Cossuet at al., submitted (2018).

Resume : ZnO nanostructures have attracted a great deal of research interest over the past few years due to their unique properties and exciting potential applications. Growth of well-ordered, large scale, periodic arrays of ZnO nanowires (NWs) using solution based processes are essential for enhancing the performance of the device and for advanced light-matter interaction control i.e. absorption and emission enhancement. The objective of this study is to demonstrate that by using chemical technique, one can synthesize different forms of nanostructures of ZnO. Selective growth of ZnO using templates fabricated by bottom-up and top-down approach has been achieved. The bottom-up approach involves fabrication of self-organized templates of functionalized polystyrene beads for two purposes, namely, as masks for patterning silicon and for fabrication of urchin-like ZnO structures [1]. In the top-down approach, different kinds of silicon patterns in the form of cones or pillars can be obtained using Laser Interference Lithography technique. ZnO NWs are grown on these patterns (pine-tree like structures) [2,3]. The structural and optical properties of these patterned ZnO NW structures will be presented. These patterned samples will be further used for device applications. [1]A. Gokarna, et al. RSC Adv, 4, 47234, 2014. [2]A. Gokarna, et al. Phys. Stat. Sol. C 13, 421, 2016. [3]A. Gwiazda, et al. Adv. Mater. Technol. 2,1700107, 2017.

Resume : The optical properties of ZnO nanowires, grown by the vapor-transport method using Au as catalyst over quartz and SiO2/Si substrates, have been characterized as a function of the growth parameters such as growth temperature, growth time and the thickness of the Au film used as catalyst. The diameter and the length of the nanowires range from 40 to 200 nm and 0.2 to 2 μm, respectively. Room-temperature absorption spectra show a well-defined exciton peak in the ultraviolet. Photoluminescence measurements show two emission bands at room-temperature, the exciton emission peak in the ultraviolet, and a very broad emission band in the visible range from 420 to 800 nm, which exhibits three distinct peak-like contributions in the Green, Yellow and Red at around 520, 590 and 720 nm (2.38, 2.10 and 1.72 eV), respectively. We show that the intensity of the broad emission band in the visible increases relative to that of the exciton emission as the ZnO nanowire diameter decreases due to a surface effect. Moreover, the intensities of the emission bands in the visible change as a function of the ZnO nanowire growth parameters, which correspond to different defect-related recombination processes. This work shows that the growth parameters influence the quantity and type of defects present in the material, which will be useful in the future applications of ZnO for optoelectronics.

Resume : Due to their outstanding anisotropic mechanical properties along the fiber axis, carbon fibers are used to reinforce polymers (CFRP) or concrete (ECC). In this context, the interface between the fiber and the surrounding matrix material plays a key role for the reinforcement mechanism. Different methods including plasma oxidation, chemical or electrolytic etching and chemical vapor deposition have been investigated in order to increase the bonding strength. The present study deals with a laser-based approach to functionalize carbon fibers. For this purpose, a fs-laser (λ = 1025 nm, τ = 300 fs, frep = 100 kHz) was used to structure large surface areas of carbon fibers with laser-induced periodic surface structures (LIPSS).The formation process of high-spatial frequency LIPSS (HSFL) with spatial periods Λ ≈ 170 nm and low-spatial period LIPSS (LSFL) with periods Λ ≈ 940 nm was investigated in dependence on the laser peak fluence and the number of laser pulses. For the first time, hybrid structures were demonstrated based on a superposition of LSFL and HSFL. The surface morphologies were characterized with scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fast-Fourier Transformation (FFT). The chemical modification was analyzed with Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Mechanical tests were performed in order to evaluate the impact of the fs-laser irradiation on the mechanical properties of the carbon fibers.

Resume : TiO2, which shows great chemical resistance and thermodynamic stability, is widely applied in many applications including photoelectrode for photoelectrochemical cell. And the hydrothermal process is well-known as a facile route for the synthesis of nanostructured TiO2. However, it requires accurate process optimizations and adjustments to prevent the products with undesirable morphology. Herein, systematically controlled experimental studies were carried out under thermodynamic and kinetic considerations to understand the formation of the well-aligned TiO2 nanorods during the hydrothermal reaction. TiO2 nanorods were synthesized on various type of substrates, including single crystals, seed mediated and thin film deposited for clarifying the preferential growth of TiO2 nanorods. Various growth parameters were studied to confirm the effects on the morphological evolution of the TiO2 nanorods. Based on the crystallographic analyses of the TiO2 nanorods and extensive monitoring on entire growth processes, the stable morphology formed by surface energy of the TiO2 nanorods was confirmed. The results demonstrate the impact of precipitation controlled by HCl concentration of the solution and what morphology can be synthesized by homogeneous and heterogeneous nucleation with hydrothermal method.

Resume : There have been multiple reports on TiO2-derived nanotubes prepared by hydrothermal synthesis method in extreme basic conditions (aq. NaOH). The hydrothermal method employed has been reported to produce a variety of compounds such as Na2Ti3O7, Na2Ti4O9.H2O, Na2Ti6O13, etc. Naturally, it generates contradictions with respect to the proposed crystal structure, composition and formation mechanism of the nanotubes. This work focuses on the preparation of titania nanotubes using microwave-synthesized TiO2 and TiO2 (P25) as precursor. The hydrothermal conditions are varied (100-180 oC; 3h-48h) and the changes in microstructure of the Na-contained tubes as well as partially ion-exchanged tubes have been analyzed thoroughly. Another quick and efficient microwave technique has been employed to prepare Na-contained titania products. It was seen that the morphology of the product was different, but the synthesis duration could be reduced to 5-10 min. Detailed electron microscopy (SEM and TEM) is performed to explore the morphology of the products and SAED patterns are used to explain the phase and crystal structures. It is observed that the leaching of Na+ ion from the structure and its replacement with H+ ion tends to affect the crystallinity and stability of the product, keeping its morphology intact. Detailed X-ray Diffraction and Thermogravimetric Analysis was done to study the effect of Na+ in the system. A rigorous analysis of the surface is provided with the help of XPS and TPR/TPD techniques. Noble metals (Au, Pt) are decorated on the surface of the nanostructures to enhance their activities as catalysts for CO oxidation. The NaTNT-Pt hybrid that shows the best activity shows a full-conversion temperature of 140 oC. The rate of reactions and activation energies are compared for the catalysts.

Resume : Biological computing systems are very inspirational objects, from their structure, organization and up to there computing principles for the development of new computing paradigms. Emulating some of these basic concepts in hardware could potentially revolutionize our way of processing information. This approach needs to consider the neuromorphic computing paradigm in its globality, from the basic sensors level to the data analysis one. In this presentation, we will put the emphasis on organic materials as a promising platform for future neurmorphic engineering solutions. In particular, we will present an innovative approach that relies on both intrinsic micro-sensors’ physics and neuromorphic computing concepts to show pattern classification out of a 12-unit bio-sensing array. We adapt the proposition of reservoir computing to demonstrate that relevant computing can be realized based on the ionic dynamics in 400-nm channel-length organic electrochemical transistor (OECT) and the key concept of learning. Furthermore, we show that this approach can deal efficiently with the high level of variability obtained by bottom-up electro-polymerized OECT. We discuss the effect of the array size and variability on the performances for a simple real-time classification task paving the way to new sensing and processing approaches.

Resume : Adequate matching of properties of multi-component hybrid molecular material can lead to tunable and functional systems that feature the combined intrinsic properties of each component and, possibly, new properties. These hybrids can be further integrated into mesoscopic architectures and lead to optimized devices or new applications. We focus our interest on the efficiency of one direction charge transfer and transport processes in hybrid molecular material for applications in solar energy through photovoltaic conversion (solid-state Dye-sensitized Solar Cells, ss-DSCs) and through photocatalysis application (PhotoElectrosynthesis Cells, DSPECs). In order to improve the charge transfer between active units (e.g. the dye and the Hole-Transport Material HTM), we introduce a covalent bond between these molecular units, thus making covalent arrays or conjugates (A. Delices et al. Electrochim. Acta (2018) 269, 163). Using in situ electro-assisted PhotoElectroPolymerization (PEP), this strategy allows the controlled deposition of a conducting polymer (CP) covalently linked to the photoactive moiety with removal of any interface between components. This approach, based on energy level matching and covalently bounded units, allows the targeting of both n- and p-type photoelectrode materials for the two above-mentioned applications. We used such obtained material in low-temperature CO2-conversion processes based on electrocatalytic and photoelectrochemical approaches.

Resume : Light-emitting diodes (LEDs) represent one of the most important technological progress of the 20th century, as it allowed us to obtain light as primary product of their working mechanism, with efficiencies as high as 80%. They are based on inorganic semiconductor materials coated with a color down-converting phosphor. However, commercial inorganic phosphors rely on rare earth materials, which leads to high production cost and uncertain availability for the future. Additionally, their bad color quality is considered a health concern.[1] This led to the rise of hybrid organic-inorganic LEDs, which feature an organic phosphor.[2] There are two major challenges in the hybrid white LED (HWLED) field. Firstly, there is the need to develop new color down-converting coatings with enhanced photo- stabilities and thermal management. Secondly, there is a strong need of white-emitting single-component down-converting coatings, to circumvent problems related to self-absorption, phase separation, and color instability caused by mixing two or more different emitters. Herein, we provide a pioneering synthesis method demonstrating the first example of single-component white-emitting hybrid organometallo-silica nanoparticles using a new synthetic approach. In short, the latter is based on the kinetic control of the initial formation of emissive organometallic dots of about 5 nm of diameter, via the condensation of three emitting iridium(III) complexes bearing terminal alkoxysilane groups, prior to the growth of the mesoporous silica nanoparticles.[3] These novel nanoparticles show one of the highest photoluminescence quantum yields for white emission (20%), that is remarkably stable under different irradiation and temperature stress scenarios. This finding encouraged us to employ the white-emitting hybrid silica nanoparticles as color down-converting coatings and/or packagings for HWLEDs. The latter featured an excellent color quality, which closely matches the sunlight spectrum, spherical light distribution, and stability over thousands of hours (<2% decrease for >1500h under continuous operation conditions). As a matter of fact, both color quality and stability of our WHLEDs are the best reported up to date. We believe that the versatility and simplicity of our new synthesis approach, as well as the excellent optical properties and stability of our hybrid nanoparticles and devices may open new and exciting opportunities for the design and fabrication of new single component white emitters and HWLEDs. [1] K.M. Zielinska-Dabkowska, Make Lighting Healthier, Nature. 553 (2018) 274–276. [2] E. Fresta, V.F. Luna, P.B. Coto, R.D. Costa, Merging Biology and Solid-State Lighting: Recent Advances in Light-Emitting Diodes Based on Biological Materials, Adv. Funct. Mater. (2018) DOI:10.1002/adfm.201707011. [3] C. Ezquerro, E. Fresta, E. Serrano, E. Lalinde, J. Garcia-Martinez, J.R. Berenguer, R.D. Costa, Three-in-one: White-emitting organometallo-silica nanoparticles for single-component hybrid light-emitting diodes, Mater. Horiz. (2018) (Submitted.)

Resume : The presenter was fascinated by the discovery of the oriented growth on an aligned poly(tetrafluoroethylene) [PTFE] layer and has been keeping the first interest for over two decades. It is a promising method for preparing ordered molecular films because of its remarkable orienting ability together with the versatility for a wide range of materials. There have been no such kinds of substrates for orienting molecules. In spite of the non-sticking and poor wetting properties of PTFE, what happens between PTFE and the materials? Then we have recently concluded that this is due to negatively charged atomic grooves of an aligned PTFE surface. This atomic groove epitaxy was first discovered by a molecular dynamics (MD) simulation [3] and furthermore some modification of the F charge recently demonstrated the significant contribution of its negative charge, which is crucial for high orientational degrees of two linear conjugated molecules[2]. In the model, the grooves between adjacent PTFE chains trap the molecules, thus accounting for the high degrees (~0.95　of order pamameter) in theirexperimentally deposited thin films on the layers. Hence, such an orientation is only possible with PTFE. This work is supported by JSPS-KAKENHI(JP17K4996). [1] J. C. Wittmann, P.Smith., Nature, 352, 414 (1991); [2] T. Tanaka, M. Ishitobi, J. Phys. Chem. B, 106, 564 (2002); [3] T. Tanaka, M. Ishitobi, Chem. Lett., 47(1), 55 (2018).

Resume : Over the last years, magneto-optically active organic compounds have been studied in great detail. They exhibit numerous applications in spintronics such as waveguides, optical magnetometers and magnetic field sensors. One of the commonly investigated magneto-optical phenomenon is the Faraday rotation, typically observed in inorganic compounds with permanent spin moments, i.e. unpaired electrons. Recent studies have been reported in the field of organic semiconductors, where organic polymers with high carrier mobility are used as the active materials while their sensitivity to magnetic field has not been explained yet. As a part of an ongoing research concerning efficient magneto-optical materials, several of conjugated polymers and liquid crystals were tested for their Faraday rotation responses. For thin organic materials at room temperature the value of Verdet constant is giant and approaches 104–105 °/Tm – which is about 1–2 orders of magnitude larger than for inorganic compounds. Using their extraordinary ability to self-assemble, which help in obtaining highly ordered structures, it is possible to improve magneto-optical rotation. By controlling the thickness of pi-conjugated polymer layers (e.g. P3HT) in the range of 50–350 nm, it is possible to increase the Verdet constant in visible spectral range. Here, for the first time, we report an observation of a giant Faraday rotation was observed for liquid crystal with copper thin film in crystalline form. The main challenge of this work is to optimize the preparation of well-oriented samples. This new approach towards organic-spintronics opens the way to develop magneto-optical phenomena in self-assembling organic structures.

Resume : Progress in the last few decades in nano-scale thermal transport has enabled a significant degree of control over heat and sound propagation by lattice vibrations - phonons. The latest investigations on the thermal properties of silicon, the most common material in electronics, micro- and nano-electro-mechanical systems (MEMS and NEMS) and photonics, have pointed to nanostructuring as a highly efficient approach to acoustic phonon engineering [1-3]. Heat conduction in silicon can be effectively engineered by means of sub-micrometer porous thin free-standing membranes [1,4]. Tunable thermal properties make these structures good candidates for integrated heat management units such as waste heat recovery, rectification or efficient heat dissipation. However, possible applications require detailed thermal characterization at high temperatures which, up to now, has been an experimental challenge. In this work we use the contactless two-laser Raman thermometry to study heat dissipation in periodic porous membranes at high temperatures via lattice conduction and air-mediated losses [4,5]. We find the reduction of the thermal conductivity and its temperature dependence closely correlated with the structure feature size. Based on two-phonon Raman spectra, we attribute this behavior to diffuse (incoherent) phonon-boundary scattering. Furthermore, we investigate and quantify the heat dissipation via natural air-mediated cooling, which can be tuned by engineering the porosity. References: 1. M. Maldovan, Nature 503, 209 (2013). 2. M.R. Wagner, B. Graczykowski, J.R. Reparaz et al., Nanoletters 16(9), 5661–5668 (2016). 3. B. Graczykowski, M. Sledzinska, F. Alzina et al., Physical Review B 91, 075414 (2015). 4. B. Graczykowski, A. El Sachat, J.R. Reparaz et al. Nature Communications 8, 415 (2017). 5. J. Reparaz, E. Chavez-Angel, M. Wagner et al., Review of Scientific Instruments 85, 034901 (2014).

Resume : Recently, mesoporous thin films with highly controlled pore systems has a significant technological value because it has emerging applications in sensing, thermoelectric energy conversion, thermal isolation, microfluidics and solar cells. Most of these application require a complete optical and thermal characterization [1]. In this work, we propose to studying the sorption, optical and thermoplamsonics properties of mesoporous films in which local heating is induced by plasmon of nanorods of gold (GNRs). Indeed, recent investigations have shown that GNRs can serve as a local source of heat [2]. Particularly, the basic system consists to fabricate a nanocomposite optical thin films composed by GNRs surrounded by mesoporous silica. The functioning of the device is based on thermo-optical properties of GNRs. In this context, we developed and optimized synthesis method that allowed us to obtain a hybrid nanostructures containing gold nanoparticles coated with silica . Mesoporous silica is grown on CTAB stabilized GNRs, silica shell can be grown in one step using the GNRs as a nucleation sites, since the capping surfactant (CTAB) is also used as a template for the formation of the porous silica. After synthesis, the colloidal particles were deposited using capillary/evaporation regime during dip coating procedure. The nanocomposite system was characterized by SEM, TEM and by in-situ ellipsometric analysis. The evolution of LSPR of GNRs during capillary condensation and desorption of water and toluene is investigated as a function of Relative Humidity (%RH). The measurements are performed in an environmental chamber allowing control of (%RH). We have quantified a 40 nm red shift with our nanocomposite system in the empty porosity (n= 1.2) – full porosity (n= 1.45). Moreover, these measurements are investigated by exciting of LSPR of GNRs inducing thermal heating. The porous SiO2 coupled with nanorods could be used as a nanoprobes for measure local temperature for GNRs and a sensitive chemical sensor to detect a contaminant of air. [1] C. D. S. Brites, M. C. Fuertes, P. C. Angelomé, E. D. Martínez, P. P. Lima, G. J. A. A. Soler-Illia, and L. D. Carlos, Nano Lett. 17, 4746−4752 (2017). [2] G. Baffou, R. Quidant, Laser & Photonic Reviews 7, 171-187 (2013).

Resume : Bimodal pore systems feature high adsorption capacity due to micro- and mesoporosity combined with macropores for good transport properties. Therefore, such systems are of utmost importance for chromatography applications or as carrier for catalysts. The inorganic sol-gel-chemistry offers reliable routes to synthesize materials with tunable pore sizes, most prominently via phase separation during condensation and solidification of silica precursors [1]. This concept was successfully transferred from inorganic to organic polymers. In contrast to previous studies on radical polymerization [2], we extend this strategy to novel bicontinuous porous polymers, which form readily under mild conditions via the cyclotrimerization of inexpensive diisocyanates. In addition, the isocyanate chemistry allows using tailored prepolymers to optimize the properties (e.g. shrinkage) or functionalizing the resulting solvogels for adjusting polarity and incorporating catalysts. Furthermore, the crosslinked polyisocyanurate network is thermally and mechanically stable and therefore suitable for applications involving high pressure or temperature. We will present the considerations leading to systems of suitable solvents and polymers for controlled phase separation, focus on the parameters for synthesis and functionalization, as well as giving a first outlook on applications. [1] K. Nakanishi, J. Porous Mat. 1997, 4, p. 67 [2] K. Kanamori, K. Nakanishi, T. Hanada, Adv. Mater. 2006, 18, p. 2407

Resume : Recent advances in two-dimensional (2D) material science have shown the importance of structural features, such as grain boundaries, on the performance of future electronic devices. At the same time, understanding how the thermal conductivity and elastic properties of polycrystalline 2D materials scales with grain sizes has become a key information for engineering efficient and scalable materials towards applications. In this work we report a record low thermal conductivity in polycrystalline MoS2 obtained by varying grain sizes and orientations in ultrathin films. By optimizing the sulphurisation parameters of nanometre-thick Mo layer, we could grow MoS2 films with tuneable morphologies. The thermal conductivity was extracted from a Raman laser power-dependent study on suspended samples. The lowest value of thermal conductivity of 0.27 Wm-1K-1 was obtained in a polycrystalline sample formed by a combination of horizontally and vertically oriented grains, with respect to the bulk (001) monocrystal. These results open the possibility use of these thermally insulating films in the context of electronics and thermoelectricity, as various theoretical studies have already suggested efficient thermoelectric generation based on MoS2 which, together with progress in transition metal dichalcogenide doping, could lead to validation of these concepts in the near future. By means of micro-Brillouin light scattering we determined the mechanical properties of MoS2 membranes in a simple, contactless, nondestructive manner. The results show huge elastic softening compared to bulk MoS2, which is correlated with the sample morphology and the residual stress. References [1] M. Sledzinska et al. 2D Mater. 3 035016 (2016) [2] M. Sledzinska et al. ACS Appl. Mater. Interfaces 9 37905 (2017) [3] B. Graczykowski, M. Sledzinska et al. Nano Lett., 17 7647 (2017)