Advanced functional films grown by pulsed deposition methods

Resume : Pulsed Electron Deposition (PED) has become a well-known vacuum technique for thin film growth of several materials. Thanks to its features, reliability and low running costs, the PED has been acknowledged as one of the most interesting sources, especially for complex compounds, and this presentation would be a review of the published literature concerning this technique. In PED, a pulsed e-beam rapidly ablates the first layers of a target material, producing an energetic plasma plume able to condensate onto the substrate surface nearby. The film growth conditions are strictly controlled by the properties of the e-beam in order to ignite atomic excitations and ionizations. Due to the nature of the beam, the shield effect of the plume is absent and the PED process shows high ablation rates useful for a wide range of materials. In addition, low costs for installation of power sources make PED as a suitable technology for massive manufacturing. Here we present a comprehensive review of the application of PED for both fundamental and applied research. Complex compounds, such as oxides, carbides, selenides, sulfides have been deposited by PED for applications in photovoltaics, superconductivity, electronics, sensors, multiferroicity, fuel cells and medicine. A wide range of structures can be synthesized by tuning the electrical parameters and the growth temperature. Finally, we present a series of next-generation materials whose physical properties could be improved by PED technique.

Resume : Our project (ADEPT, EPSRC EP/N035437/1) aims to produce nanowire devices from main group semiconductor materials through electrodeposition into hard templates. This part of the work focuses on fabricating nanoscale composites by templated electrodeposition. Silica films with a well-ordered three-dimensional mesoporous structure were prepared by the evaporation-induced self-assembly (EISA) method. Grazing incidence small-angle X-ray scattering showed that the pore structure adopted the Fmmm space group with [010] orientation. Bismuth and tellurium were grown through the 3D mesoporous channels by conducting two-step pulsed electrodeposition in a non-aqueous electrolyte system. Electrodeposition conditions were used to optimise the nucleation and growth process and to maximise pore filling. In situ grazing incidence small-angle neutron scattering was used to follow Bi electrodeposition into the pores and to link variations in nucleation to differences in the grown material.

Resume : Ge-Sb-Te (GST) based thin films are of high interest due to their outstanding optoelectronic properties and represent the basis of various non-volatile data storage technologies. The need to understand the correlation between thin film structure and properties calls for research in the synthesis and characterization of epitaxial GST thin films, which offer a significant potential for both basic research and the development of new concepts for memory devices. In this work, layered epitaxial Ge2Sb2Te5 (GST225) thin films consisting of GST building units separated either by vacancy layers (vacancy ordered metastable phase II) or by van der Waals gaps (vacancy ordered stable phase) were achieved on Si(111) substrates by pulsed laser deposition. The formation of a particular phase during the growth was strongly dependent on the deposition process parameters such as substrate temperature, laser fluency and partial pressure of Argon gas. For example, a variation of the laser fluency led to the formation of metastable or stable phase. Nanoscale characterization by transmission electron microscopy revealed the local atomic order and defects in the thin films. UV-laser irradiation of the layered GST225 thin films resulted in the epitaxial recrystallization into non-layered GST225 films (vacancy disordered metastable phase I). Optical characterization of the GST225 thin films revealed the correlation of structural order with the properties of thin films. The Tauc parameter, dielectric constant and plasma frequency obtained from optical spectra are increasing with the improvement of degree of structural order. In addition, the results showed the delocalization of free charge carriers, which evidences the insulator-to-metal transition.

Resume : TiAlN single layer HiPIMS coatings were performed and later characterized to study the effects of different process parameters on the film stoichiometry, the microstructure, the surface morphology and the thickness. Besides, the influence of these process parameters on different mechanical properties were also determined. For more comparison study, the properties of same TiAlN coatings produced by dcMS and by Arc were also carried out. Only the most influence process parameters which are the effect of duty cycle, pressure, power and bias will be reported. TEM and SEM observations indicate that the morphology of TiAlN coatings displayed for all the applied conditions a similar columnar morphology, with columns extending from the substrate to the surface. With XRD analyses it was shown that TiAlN coatings deposited by Arc and by HiPIMS have a single-phase cubic structure with (200) and (111) dominant texture as a preferred orientation, respectively. The residual stress also determined by XRD for the HiPIMS coating samples can change from tensile stresses to compressive stresses depending on the different process parameters. Special emphasis to control the stress level of the HiPIMS coatings and consequently to tune their mechanical properties will be proposed. Particularly the residual stress generation and evolution in the film, as well as the hardness, were determined. It is shown that the applied bias plays a key role to improve the film mechanical properties.

Resume : Transparent and amorphous Yttrium containing Sialon thin films were successfully fabricated by pulsed laser deposition (PLD) for high technology applications such as protector for smart display screens, army vehicles windows, and liquid crystal display, etc. A thin films were fabricated in three steps; first, Sialon target was synthesis by spark plasma sintering technique at 1500 C in inert atmosphere, second, the surface of the fabricated target was cleaned by standard grinding and polishing technique to remove and avoid any contamination on the surface of the target such as graphite sheet, and finally, Sialon target used for thin films by pulsed laser deposition in the inert atmosphere. The morphology, optical, structural, mechanical, and compositional properties of the fabricated thin films were investigated at different deposition parameters such as substrate temperature, laser power and frequency, deposition time, and deposition pressure. Keywords: AE/RE-Sialon; thin films; Ultra-hard; Pulsed laser deposition.

Resume : Among various physical vapor deposition, (PVD) processes used to produce graphene, as an alternative route to chemical vapor deposition (CVD) processes, pulsed laser deposition (PLD) is a versatile process to synthetize graphene materials in a controlled and reproducible way, including dopant incorporation to modulate the graphene properties. A parametric study was performed to optimize the thickness of the amorphous carbon (a-C) film (within 1 and 20 nm) and the thermal heating temperature (within 800 and 1000°C in vacuum), to produce a dominant bilayer low-defective graphene film. From those optimal conditions, boron was incorporated into the graphene layers by co-ablating carbon an boron to form an amorphous boron-doped carbon film (a-C:B) converted into boron-doped graphene by thermal heating. The nanoarchitecture and defect content of the graphene and boron-graphene films were investigated by Raman spectroscopy and mapping (including over large areas up to 100 × 100 μm²), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). This study presents experimental guidelines for optimal synthesis conditions to control (doped-) graphene growth by pulsed laser deposition.

Resume : Creating DLC films on polymeric substrates using the PLD technique is increasingly attracting scientific interest owing to the simplicity of this technique and the convenience of the room temperature process conditions. Initial research focusing on the development of DLC films on biomaterials for medical applications has indicated that the diamond-like carbon structure can be successfully obtained on soft materials, which has promoted a new area of DLC application. Much work is this area focuses on the impact of the substrate on the DLC film, in terms of the demanding requirements for implants and devices. However, the effect of the DLC film on the polymeric substrate material also needs to be defined. The aim of our work was to produce DLC films on different polymer substrates and to study the interaction between them, especially alterations of the chemical structure. A graphite target was ablated with a KrF laser in vacuum at room temperature. The structure of the DLC films obtained and of the substrates was studied using Raman, Infrared, Nuclear Magnetic Resonance and X-ray photoelectron Spectroscopy. The morphology of the films was evaluated by SEM and AFM methods. It was found that, depending on the type of polymer and the fluence of the laser used, chemical changes in the polymer chains can occur to varying degrees. In addition, even for one type of polymer, physical properties such as crystallinity can have an important effect.

Resume : Atomically-thin two-dimensional (2D) materials face significant energy barriers for synthesis and processing into functional metastable phases, such as Janus structures. Pulsed laser deposition (PLD) plasmas inherently imbue species with kinetic energies (KEs) ranging up to 100 eV/atom. These can be moderated through collisions with background gases. Here we explore the synthesis and conversion of few-layer atomically-thin 2D transition metal dichalcogenide crystalline films by PLD using in situ diagnostics to control KE < 10 eV/atom, a regime that excludes other techniques such as sputtering or MBE. We introduce and characterize the controllable implantation of hyperthermal species from pulsed laser deposition (PLD) plasmas as a top-down method to compositionally engineer 2D monolayers. Using in situ plasma diagnostics the kinetic energies of Se clusters impinging on suspended monolayer WS2 crystals were controlled in the <10 eV/atom range to determine the thresholds for selective top layer replacement of sulfur by selenium for the formation of high quality WSSe Janus monolayers at low (300 °C) temperatures, and bottom layer replacement for complete conversion to WSe2. Atomic-resolution electron microscopy and spectroscopy in tilted geometry confirm the WSSe Janus monolayer. Molecular dynamics simulations reveal that Se clusters implant to form disordered metastable alloy regions, which then recrystallize to form highly ordered structures, opening the door for low-energy implantation by PLD as a novel method to explore the synthesis of 2D Janus layers and alloys of variable composition. Research was sponsored by the U.S. Dept. of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Div. and was conducted at CNMS, a U.S. DOE Office of Science User Facility.

Resume : Chromium oxide (Cr2O3) and Magnesium (Mg)-substituted Cr2O3 thin films at various concentrations have been deposited using pulsed laser deposition (PLD) techniques. Structural, optical and electrical properties were recorded using X-ray diffraction (XRD), UV-Vis spectroscopy and four-probe method. XRD results confirmed the epitaxial growth of as-deposited thin films and crystallize in rhombohedral structure with space group R-3c. And its structure remains unaffected with Mg-substitution. But expansion along c-axis has been observed with the increase in concentration due to higher ionic radii of Mg2+ (86 pm) as compared to Cr3+ (75.5 pm) ion. UV-vis measurements demonstrated high transparency in the visible region of as-deposited thin films. The optical band gap of thin films was determined using Tauc’s relation. Pure Cr2O3 thin film exhibits a wide optical band of 3.66 eV, which was found to decrease with Mg-substitution. Electrical measurements revealed that pure Cr2O3 thin film has high resistance of the order of 105 Ω. After the substitution of Mg into Cr2O3, enhancement in conductivity has been observed. Hall measurements confirmed that Cr2O3 thin films retain the p-type character, even after the Mg-substitution. This work can lead to the development of highly effective p-type transparent conductive oxide material, which can render application in the field of optoelectronics.

Resume : Present work reports a simple, cost-effective and scalable approach for electrochemical sensing employing silver thin film electrodes prepared by the single-step AACVD with controlled and optimized microstructure to have Ag nanoparticles coalesced together for high conductivity and facile electrochemical reduction of 2-nitrophenol (2-NP) as the model analyte. Thickness controlled structure and conductivity evolution of the silver thin films is studied by growing them on ITO glass substrates at 400 ˚C for deposition times of 10-45 minutes using methanol solution of silver triflouroacetate (Ag(CF3COO)), a commercially available precursor. XRD, XPS, SEM and EDX analysis of the films verified the presence of crystalline and phase pure elemental silver with nanometer dimensions. All silver electrodes were used to investigate the electrochemical behavior of 2-NP by cyclic voltammetry (CV) while the quantitative profiling was done by LSV. The results indicate that the silver electrode developed in 30 min has an excellent electrocatalytic activity toward 2-NP reduction in terms of lowering the reduction overpotential and increasing the reduction current which is attributed to its percolated metallic network structure. This particular electrode exhibit a wide dynamic range = 50-450 M, detection limit = 12 nM, signal loss = 3.4% over 4 weeks, and high selectivity from potential interfering agents, a performance much better than the available thin film sensors and Ag-disk electrode.

Resume : The deployment of the 5th Generation of mobile applications (5G) requires RF filters with improved performances in terms of frequency, fractional bandwidth, and so on. Due to its high electromechanical coupling coefficient (up to 45% for bulk waves), acoustic velocity (3500 – 7500 m.s-1) and quality factor (> 45000), single-crystal lithium niobate (LiNbO3) thin film appears as an appealing candidate to replace AlN-based materials in these devices [1]. LaNiO3 is a conductive ceramics with a lattice parameter close to LiNbO3. It may be used as a seed-layer and an electrode for BAW applications. In the present work, approximately 200 nm-thick LiNbO3 films have been grown by Pulsed Laser Deposition (PLD) [3] on LaNiO3/Si samples. The as-deposited films have been characterized by X-Ray diffraction, Raman spectroscopy, Atomic Force Microscopy (AFM) and ellipsometry. The stoichiometry of the film seems difficult to control and the roughness significant. Finally, electrical properties and in particular piezoelectric properties (d33 coefficients) have been evaluated. References [1] A. Bartasyte et al., Advanced Materials Interfaces 4, 1600998 (2011). [2] E. Dogheche et al., Japanese Journal of Applied Physics 42(2A):572-574 (2013). [3] D. Blank et al., Journal of Physics D, Volume 47 Number 3 (2014).

Resume : Full-color reflective filters for large area applications with potentially unprecedented color saturation and excellent mechanical properties deposited by one-step magnetron sputtering were proposed. Conventional reflective color filters with multiple layers of dielectric films could not simultaneously produce a large area and good mechanical properties due to the complex multiple depositions and the difference in the thermal expansion coefficients among the material layers. Herein, full-spectrum colors were generated by novel Mg-based reflective color filters in a large area of 2 cm × 2 cm with a high hardness of 9.12 GPa, where the filters include an absorber layer with controllable optical constants and a reflective layer with an amorphous structure. The saturation and hue of the produced colors can be controlled by tuning the optical constants and the thickness of the absorber layer. Additionally, the hardness of the Mg-based reflective color filters was increased by the reflective metallic glass layers because they were derived from the same material as the absorber layer. This paradigm could pave the way for the efficient fabrication of large area color filtering devices for diverse applications, such as surface decorations, optical components, color display devices, structural color printing and photovoltaic cells with optimum efficiency.

Resume : In this study, Eu3+ doped SrLaMgTaO6 (SLMTOE) thin films were deposited on SrTiO3 (100) using pulsed laser deposition, and the dependence of the structural and photoluminescence (PL) properties on the oxygen partial pressure was investigated. The X-ray diffraction patterns were investigated to determine the growth behavior of the SLMTOE films on the SrTiO3 (100) substrates. Under an oxygen partial pressure of less than 100 mTorr, the SLMTOE film deposited on the SrTiO3 (100) substrate was aligned out of the substrate surface, while at high oxygen partial pressure it was not. The PL spectrum showed that the red emission peak at 613 nm was strongest at the oxygen partial pressure of 100 mTorr, and the emission peak intensity decreased with increasing oxygen partial pressure. In addition, X-ray photoelectron spectroscopy (XPS) analysis showed that the content of Eu3 + ions decreased with increasing oxygen partial pressure, while the content of Eu2 + ions increased.

Resume : Zinc oxide (ZnO) based materials demonstrate attractive properties for different modern technological applications. Doping of ZnO with transition metal (TM) elements offers an effective method to adjust its electrical, optical, and magnetic properties, which is crucial for its practical applications. The present work is devoted to preparing of Zn1-xMexO (Me: Mn, Ni, Co) thin films by RF-plasma sputtering technique and study of their structural, optical and magnetic properties depending on content of TM elements. The content x in the deposited films was varied in range of (0 – 0.1). The structures of the samples have been studied by using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The structure and surface morphology of the deposited layers show strong dependence on doping with TM and deposition conditions. The optical absorption spectra of the films demonstrate that the energy bang gap was found to decrease with increase of Co content and complex dependence on the content of Ni. The EPR spectra show a broad asymmetrical line of Dysonian shape and satisfactory ascribed by the single Lorenz type curve with Dysonian term. Near the ferromagnetic ordering temperature distortion of the EPR spectra and its following splitting on two Dysonian lines were found.

Resume : The influence of sputtering parameters on the microstructures of Cu-Ni thin films was investigated in this study. The Cu-Ni thin films were fabricated on p-type silicon substrates by magnetron sputtering deposition at various sputtering powers and Ar pressures. The microstructures of these films were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results shown that the Cu-Ni film deposited at higher sputtering power and lower Ar pressure promoted the film crystallinity and the growth of Cu-Ni films as compared to the films deposited at lower sputtering power and higher Ar pressure due to the increase of the surface mobility of the adatoms with higher energy and decreasing Ar pressure. The crystallite sizes of the Cu-Ni films as a function of deposition rate are also discussed in this study. The crystallite sizes of the Cu-Ni films analyzed using Scherrer?s formula shown a linear relation with deposition rate. However, the deposition rate seems not exhibit strong effect on the alloy composition of the film. The surface morphology of the Cu-Ni alloy films studied by SEM revealed the surface microstructural variations in Cu-Ni films deposited at different sputtering powers and Ar pressures. At higher sputtering power and Ar pressure, a cauliflower-type structure with groups of grains separated by small valleys started to form. This phenomenon reveals an important fundamental relationship between sputtering parameters and microstructures of Cu-Ni thin films that can be exploited for material design.

Resume : Silicon nitride thin films fabricated using plasma enhanced chemical vapor deposition (PECVD) have been studied as barrier films for protecting devices from moisture and oxygen in the field of organic electronics. In particular, flexible organic electronics, which have received much attention recently, require substrates having excellent barrier performance because they are very sensitive to moisture and oxygen. In this study, multilayer barrier films composed of SiNx and SiOF were continuously coated onto PET substrates by R2R PECVD at less than 50 °C in the same reactor respectively. SiH4 and NH3 gas were injected into the gas shower head as a precursor to form a SiNx thin film, and SiF4 and N2O gas were injected to form a SiOF thin film. This multilayer structure allows the decoupling of defects between the single SiNx layers In addition, SiOF is an inherently hygroscopic material that traps water molecules passing through the SiNx layer and delays the time passing through the entire barrier film, thereby contributing to the improvement of barrier performance. Furthermore, this multilayer barrier film process can be carried out continuously in a single reaction chamber without vacuum interruption, saving time compared to organic-inorganic multilayer structure. The SiNx/SiOF/SiNx multilayer film showed superior barrier performance compared to the SiNx single layer film under the same thickness. Barrier performance was measured by the water vapor transmission rate (WVTR) method using the MOCON Aquatran-2 instrument. Under the optimal process conditions, the moisture barrier performance of the SiNx/SiOF/SiNx multilayer barrier film on PET reached 1.2×10-3g/m2·day at 40 °C and 90% relative humidity.

Resume : The insulating ferrimagnets of rare-earth iron garnets (ReIG) are researched intensively owing to their strong magneto-electric responses and magneto-optical properties [1]. The ferrimagnetic Tb3Fe5O12 (TbIG) thin film (40 nm) was grown on (111) oriented Gd3Ga5O12 (GGG) substrates by using pulsed laser deposition technique [2] showing the high crystalline quality and sharp interfaces. Here, we report the use of polarized neutron reflectometry (PNR) [3] to study the magnetic properties of a Tb3Fe5O12 film at temperatures above, below and near the compensation point (Tcomp. ~ 246 K). The magnetization of the TbIG film is supressed around Tcomp. The neutron reflectivity with different states (spin up (R+) and spin down (R-)) was measured as a function of the scattering vector Q. The PNR spectra at 7 K shows the clear splitting of R+ and R- confirming ferrimagnetic behaviour for the TbIG layer. The spin asymmetry (SA = (R+-R-)/(R++R-)) results are consistent with those obtained by the temperature dependence of the magnetic moment. The scattering length density (SLD) models were used to successfully fit the data. The presence of an induced magnetic layer at interfaces between the TbIG layer and the GGG substrate is attributed to a magnetic proximity effect. Research was supported by MOST of Taiwan, RGC of HKSAR (PolyU 153027/17P), and ANSTO of Australia. [1] D. Louca, Phys. Rev. B 80, 214406 (2009). [2] Y. K. Liu et al., J. Magn. Magn. Mater., 468, 235 (2018). [3] G. L. Causer et al., Jpn. J. Appl. Phys. 59, SAAC03 (2020).

Resume : As a class of versatile materials, transition metal oxides (TMOs) with a perovskite structure have gained much interest owing to the wealth of different functionalities. The wide spectrum of TMO physical properties is strongly influenced by the interplay among charge, spin, orbital and lattice degrees of freedom. The relation between spin order (SO) and orbital order (OO), coupled to lattice distortions in TMOs, has stimulated many experimental and theoretical works. The vanadate RVO3 perovskites (R=rare earth) exhibit the prototypical behavior arising from these different couplings. Upon decreasing temperature, they undergo orbital and spin orderings at temperatures T_OO and T_SO, respectively. Interestingly, a G-type orbital ordering takes place at T_OO concomitant with a structural phase transition (orthorhombic to monoclinic). Below T_OO, superexchange interactions stabilize a C-type antiferromagnetic spin order at T_SO. Remarkably, it has been shown that T_OO can be tuned either by chemical pressure, by decreasing the R-site ionic radius, or physically by applying hydrostatic pressure, suggesting an intimate orbital–lattice coupling. Here, we present the study of the properties of PrVO3 epitaxial films grown on SrTiO3 substrates by pulsed laser deposition (PLD). A Detailed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) investigation reveals interesting magnetic behaviors of both vanadium and praseodymium sites.

Resume : he development of functional thin film materials is often characterized by typical three steps: the deposition process, a structural preparation and the characterization of the physical properties. Each of these steps is a separated by atmospheric handling and preparation activities. In case of reactive materials such preparation could be done under controlled conditions in glove boxes. But also under protected gas conditions any atmospheric gas contact to the sensitive surface of a complex multi layer film could affect the final film properties. A flexible and adaptable substrate carrier system in combination with interconnected systems could help to avoid atmospheric preparation steps and the possibility of negative influences to the film properties. The complexity of the film itself and the final characterization process demanding the kind of insitu inter action at the sample carrier level. Two ways exist to implement the structural process of the sample: for simple substrate preparation: flexible carrier based shutter/mask system for complex film or device oriented sample preparation: advanced mask system with ex changeable shadow masks and an integrated mask changing station as part of a multiple process cluster deposition system. In the first case a carrier integrated shutter/mask system allows during the process to shutter differ- ent areas of a sample. This can be actuated from the outside by dedicated manipulation devices and can be done even at the deposition temperature. The shutters are never touching the sample surface at any time. In case of more complex shutter/masking steps the carrier system has to allow the changing of precise masks between the different process steps. A separate mask changing station is necessary to store and exchange the different masks. The final design of these components must always recognize the ther- mal interaction with the substrate and its deposition temperature. The final structure width of the multiple masking processes depends of the proper handling of this thermal management between substrate and mask system. Examples for both versions are shown, including the different steps of in vacuum sample preparation.

Resume : Transparent conducting oxides (TCO) have attracted great attention since the first demonstration in 1907 by Baedeker. TCO thin films with high transparency and electrical conductivity have been widely used in optoelectronic devices, such as thin-film transistors, perovskite solar cells, organic light-emitting diodes (OLEDs) and quantum dot light emitting diodes (QLEDs). Er doped ZnO films exhibit higher optical transparency (~95 %) than other reported metal elements doped ZnO TCO thin films. The effect of Er doping concentration on photoelectric properties of ErZO thin films was investigated in the range of 0-2.0 wt.%. The Er impurity substitutes the Zn site and ErZn serves as charge donor in the ZnO crystal structure, thus resulting in the improvement of n-type conductivity as compared with intrinsic ZnO thin films. The optimized ErZO thin films present the low resistivity of 3.4×10−4 Ω/cm, high carrier concentration of 5.9×1020 /cm3 and high visible optical transmittance (~93%) when the Er content is 1.0 wt.%. The ErZO thin films were used as transparent anodes to fabricate organic light-emitting diodes (OLEDs). Impressively, with the ErZO as anode, the current efficiency of the OLEDs device can reach as high as 86.5 cd/A, which was increased by 14% when compared with the reference OLEDs device (76.0 cd/A) using ITO as anode.

Resume : Secure authentication of one’s identity is a major challenge in a modern society due to the increasing popularity of mobile devices (such as smart phones) that can not only store the owner’s personal information but also allow banking transactions. A biometrics-based authentication system has attracted a great attention owing to its relatively high-security level and convenience. Current fingerprint recognition systems do not meet the required security level: optical sensors are hard to miniaturize and easily deceived, and capacitive detectors often fail to recognize the patterns by contamination. The ultrasound technology with pMUT (piezoelectric micromachined ultrasound transducer) is one of the most promising technologies to realize such a highly-secure biometrics-based authentication system for mobile electronics. The performance of pMUT is directly determined with the electromechanical property of the piezoelectric layer. However, using conventional piezoelectric materials such as AlN, ZnO, and PZT, it is difficult to generate high power ultrasound that can penetrate into the skin to see veins. Therefore, it is highly desirable to integrate single crystalline relaxor-ferroelectrics, so-called giant piezoelectric materials, on Si substrate. In this talk, I will discuss the recent progress on the epitaxial integration of Pb(Mg,Nb)O3-Pb(Zr,Ti)O3 thin films on Si.

Resume : Gate electric-field control of d-electron magnetism in transition metal oxides is attracting widespread interest for the foreseen applications. Spin-orbit coupling in magnetoelectric compounds, when presents, may offer novel functionalities[1] and, the understanding of the underlying physics is a necessary step towards a rational design of novel magnetoelectric-based devices. Here, we report on Fe L3,2-edges X-ray magnetic circular dichroism study performed on 64 nm thick films of Ga0.6Fe1.4O3(GFO) grown onto SrTiO3(111) single crystals. Depending on the external magnetic field orientation the orbital magnetic moment is found parallel or anti-parallel to the spin magnetic moment. This apparent local violation of the third Hund’s rule is qualitatively discussed in term of strong anisotropic FeO6 distortions. The latter set a preferential crystallographic direction for the orbital magnetic moment, and the resulting strong orbital-lattice interaction may limit its reorientation in an external magnetic field. A control over the FeO6 distortions can offer a suitable leverage over the amplitude of the spin-orbit coupling in the GFO multiferroic system. [1] Manipatruni, S.; Nikonov, D. E.; Lin, C.-C.; Gosavi, T. A.; Liu, H.; Prasad, B.; Huang, Y.-L.; Bonturim, E.; Ramesh, R.; Young, I. A. Scalable Energy-Efficient Magnetoelectric Spin–Orbit Logic. Nature 2019, 565 (7737), 35–42.

Resume : In tunable ferroelectric microwave capacitors (varactors), a permittivity of an oxide (BaSr)TiO3 (BST) dielectric layer and, therefore a capacitance of the device is tunable with external electric field. They are typically produced as metal-insulator-metal (MIM) heterostructures in which the electromagnetic skin depth of the order of several micrometers in the frequency range of a few gigahertz determines the desired electrode thickness. Here we present Pt-BST-SrMoO3 varactors, combining a highly conducting perovskite oxide SrMoO3 bottom electrode with atomically engineered sharp interfaces to the substrate and to the subsequently grown epitaxial layer of a tunable BST dielectric [1]. The several micrometers thick layer-by-layer grown SrMoO3 films show a room-temperature conductivity higher than 30 kS/cm and provide a perfect lattice match to the BST of the Ba:Sr=50:50 composition range desired for high tunability of the varactors at room-temperature [2]. The difficult to achieve epitaxial thick film growth makes use of the extraordinary ability of perovskites to accommodate strain by adjusting their lattice constant with small shifts in the cation ratio. We show that our approach enables the fabrication of varactors based on 50–100 nm thin BST layers with high tunability above three at the Li-ion battery voltage level (3.7 V). [1] P. Salg et al., APL Mater. 7, 051107 (2019). [2] A. Radetinac et al., Appl. Phys. Lett. 105, 114108 (2014).

Resume : Wound dressing materials can play a vital role in wound healing management. Some of the major requirements from a wound dressing are to; absorb exudates, prevent infection and contaminant contact with wound, sustain non-toxicity, moist environment, permeability, temperature, and pH. An ideal wound dressing does not only act as a physical barrier for wound against mechanical trauma but also accelerate the healing process and prevent bacterial infection. In this regard, the development of wound dressings can be discussed taking account of traditional and modern (advanced, smart) dressings into consideration. In recent years, studies on the functionalization of conventional textile surfaces have become widespread. Particularly in medical applications, there are considerable studies on wound dressings. In this study, it is aimed to develop waterproof and antibacterial films for the top layer of a multi-component wound dressing by pulsed deposition method. As briefly discussed above, one of the important properties of the wound dressing materials is being a barrier against the risk of infection between wound and environment to prevent the external effects such as bacterias, contaminated fluids etc. In addition to these functions, the breathability of the structure is a key factor that directly affects the healing process. Therefore, the surface is coated with a waterproof and antibacterial monomer at nano scale. The nanoscale coating did not affect breathability negatively. In addition, it is aimed to increase the air permeability by using channel cross-section PLA (poly-lactic acid) yarns in the fabric structure.

Resume : Pulsed electron beam deposition (PED) is now a well-established method to grow oxide thin films, superlattices or heterostructures on rigid or flexible substrates. Besides this classical aspect, PED working under a low oxygen pressure, controls the oxygen incorporation and therefore the stoichiometry of the oxide films, leading to the growth of oxygen deficient metastable phases which can not be obtained in bulk form. The non-stoichiometry (cation-to anion ratios) will be presented in the particular case of indium oxide based thin films (In2O3, ITO, IGZO) in relation with their structure and optoelectronic properties. The effect of pulsed aspect of the growth (kinetic energies of species arriving at the substrate and the deposition rate) on the film properties was investigated. In the case of a high non-stoichiometric indium tin oxide, a phase separation occurs with the formation of metallic clusters embedded in a stoichiometric crystalline indium tin oxide matrix. Such metallic clusters induced very specific transport properties; otherwise the films are still degenerate semiconductors. These results will be presented and discussed in the frame of growth-induced non-stoichiometry vs. existing density functional calculations on electronic structure.

Resume : Al2O3 protective coatings deposited by Atomic Layer Deposition (ALD) have attracted considerable attention in the past years. With respect to many other deposition techniques, ALD has the ability to coat conformal coatings on complex geometries and, due to the low porosity, Al2O3 films grown by ALD have been recently proposed as protective coatings against corrosion in several applications. In this work we compare the structural and mechanical characteristics of 150 nm thick Al2O3 coatings fabricated by ALD and radio frequency sputtering. ALD coatings were deposited on Si substrates at 150°C and 300 °C starting from tri-methylaluminum (TMA) precursors and were submitted to annealing in air at 900 °C inside a tubular furnace. Radio frequency sputtered Al2O3 films where grown at room temperature at a radio frequency power of 300 W in pure Ar atmosphere. Samples were submitted to annealing in air at 900°C. X-ray diffraction and nano-hardness measurements were used to infer the structural and mechanical properties of the as deposited and annealed ALD and sputtered films.

Resume : With demand on the miniaturization of devices with better electrical performance, multicomponent metal oxides prepared by atomic layer deposition (ALD) have drawn great attentions as active material of thin film transistors (TFTs) or transparent conductive electrodes (TCEs) of high-end future electronic devices owing to its high mobility and extreme conformality. However, a noticeable variation of physical properties consequence of heterogenous layer-by-layer deposition manner of ALD is less explored. To address this issue, we report the influence of a bilayer period of ALD on the growth behavior, microstructures, and electrical properties of In-Zn-O (IZO) films. IZO films with various bilayer periods are deposited by alternately stacking of ZnO and In 2 O 3 layers at a temperature of 200℃. Film growth behavior, structural, electrical properties and chemical composition of ALD-IZO films were systematically investigated to verify the effect of bilayer period on IZO films. The IZO films with the number of successive ZnO cycles from 1 to 4, which are designated as IZO (9:1) and IZO (36:4) exhibit an amorphous-like phase with resistivity of 4.94×10 -4 Ω∙cm. However, IZO films with increasing successive ZnO ALD cycles showed a microstructure transition from well-blended amorphous to polycrystalline nanolaminate resulting from the lack of intermixing. The rapid increase of resistivity was observed in polycrystalline nanolaminate with a decrease of both carrier mobility and concentration. These results reveal the importance of bilayer period on designing ALD stacking sequence in the multicomponent oxide ALD process.

Resume : Ta doped tin-niobate Sn2Nb2-xTaxO7 thin films with pyrochlore structure were fabricated by pulsed laser deposition. Thin films were grown on glass and c-sapphire single crystal substrates at various substrate temperatures and nitrogen partial pressures. The effects of the processing parameters on the crystal structure, electrical and optical properties of Ta – doped tin- niobate thin films were analyzed by XRD, AFM, four point probe method, and UV spectrometer. As the doping concentration x increased, the electrical conductivity increased up to x=1.0. The optical transmittances increased with increasing substrate temperature up to 400℃.

Resume : The continuous advances in microelectronic and medical fields require the design of miniaturized and powerful energy sources. Li-ion systems are good candidates to meet these needs thanks to their high energy and power density, long cycle life, design flexibility and so on. One key way to manufacture microbatteries is the production of 2D electrodes by the means of thin film deposition techniques. Here thin films of TiO2 (anode material) were deposited by fs-PLD technique, with a Nd-glass laser source (527 nm, 250 fs, 10 Hz). The use of a femtosecond pulse laser guarantees the stoichiometric transfer of the ablated material from the target, with no need to work in an oxidizing atmosphere. Since TiO2 exists as to main polymorphs (rutile and anatase), whose presence is very sensitive to the crystallization temperature, post-treatments of annealing were carried out on the films at different temperatures. The obtained films, characterized by microscopic, spectroscopic and diffractometric techniques, were crystalline, dense and compact. Electrochemical tests confirmed the possibility to use TiO2 deposited thin films as anode for Li-ion microbatteries.

Resume : Magnetite (Fe3O4) and wustite (FeO) are well-known oxides for their tremendous magnetic properties. However, being able to grow stable FexOy thin films with controlled iron oxidation states could be of interest for further applications. In this work, we highlight the formation of different FexOy based thin films grown by pulsed-laser deposition (PLD) from Fe or Fe3O4 targets onto sapphire or MgO substrates. Based on XRD and RBS analysis, we point out that, by controlling both the substrate temperature and the oxygen pressure in the 10-7 – 0,1 mbar range during the PLD growth, films with various Fe/O ratios may be prepared. Thus, the different crystalline phases of the Fe-O system may be obtained: Fe2O3, Fe3O4, and the thermodynamically metastable FeO. In particular we show that at low pressure (10-6 mbar) Fe3O4/Fe composite thin films for which both metallic Fe and Fe3O4 phases are epitaxially grown on the sapphire substrates even at room temperature. This result is interpreted as a possible phase separation from the FeO metastable phase. The precise growth conditions leading to the formation of FeO-based film are also discussed.

Resume : Perovskite-structure rare earth nickelates such as NdNiO3 (NNO) display a pronounced metal-to-insulator transition (MIT). Being attractive for electronic applications, the MIT in thin NNO films was widely explored in the last decades. Despite significant research efforts, scaling of NNO resistivity as a function of deposition technology is far from clear comprehension. Here, we focused on in situ pulsed laser deposition (PLD) of the NNO films. Because properties of perovskite oxides are known to be sensitive to oxygen stoichiometry, we investigated resistivity of the NNO films in dependence on pressure of oxygen ambience in PLD. To enable epitaxial growth, the (001) single-crystal substrates (LSAT, LAO, STO) were used. The 20-100-nm thick NNO films were grown by PLD using an excimer KrF laser and stoichiometric ceramic target. The energy density of 2 J/cm2 and the substrate temperature of 700 C were employed. The oxygen pressure during PLD and post-deposition cooling was varied from 0.1 to 20 Pa. The high-temperature metal-type resistivity and low-temperature insulating state were obtained in the stoichiometric films deposited at 20 Pa. With decreasing PLD pressure, the resistivity was found to increase and MIT gradually vanish. It was suggested that oxygen vacancies can produce disorder in crystal and electronic structure of NNO and also act as traps for charge carriers. Consequently, the defects can lead to the relative uplift of resistivity.

Resume : Hydroxyapatite, as major inorganic component of bone, is biocompatible with tissues when used on implants. However, there are still reported surgical site infections, which are particularly critical and difficult to treat. The main goal of the research is to provide antibacterial efficacy by nano-thick and nanostructured silver-doped hydroxiapatite coatings, potentially capable of assuring a tailored ion-release, also engineered to prevent cytotoxicity and the development of resistant bacterial strains. High power impulse magnetron sputtering of a silver target and the RF magnetron sputtering of three hydroxyapatite targets, operated in Ar, were used to synthesize Ag-doped hydroxyapatite thin films. The fine control of the silver content in the deposited thin films composition was possible by the HiPIMS discharge, due to the fine control of the Ag deposition rate, by using different pulse frequencies and pulse duration periods. The content of Ag spanned from 12 to 0.5 at.%. The films deposited on polished Ti discs were characterized by various analytical techniques (AFM, SEM, EDS, RBS, XRD and FT-IR) in terms of surface morphology and texture, crystallinity, chemical and elemental composition. In vitro corrosion resistance was carried out in simulated body fluid. While low Ag content indicated no significant modifications of films properties, higher contents increased the corrosion resistance and hydrophilicity and decreased the surface roughness. This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation CCCDI - UEFISCDI,project no COFUND-ERANET EURONANOMED 3-NANO-VERTEBRA, within PNCDI III, and by the Core Program 18N/2019.

Resume : Spinel LiFe5O8 (LFO) has attracted considerable attention of research due to its high saturation magnetization, high Curie temperature, large electric resistivity, low loss at high frequencies, and good chemical stability. In this work, the microstructural properties and the growth behavior of the LFO films prepared on (001)-oriented SrTiO3 (STO) substrates have been studied by advanced transmission/scanning transmission electron microscopy techniques. Two types of orientation relationship between LFO and STO have been determined, cube-on-cube and (111)[1 ̅10]LFO//(111)[11 ̅0]STO. It was observed antiphase boundaries (APBs) and three types of twin boundaries (TBs) form within the films, and misfit dislocations with the displacement vector of (a/4)[110] form at the interface. The propagation of TBs and APBs results in their complex interactions in the films. In most cases, interactions between TBs and APBs can change the type of TBs and terminate the propagation of APBs since the APBs introduce a displacement vector of (a/4)[110] into the TBs. In addition, the interactions between two coherent TBs are observed to generate the incoherent TBs. The epitaxial misfit strain of the heterosystem can be released by the formation of TBs, APBs and misfit dislocations. The cation distributions across the APBs and three types of TBs result in different magnetic couplings and novel physical properties compared with the perfect spinel structure. Consequently, the magnetic properties of the LFO films would be affected by the appearance of a high density of APBs and TBs within the films.

Resume : Copper oxide Cu2O is an important and well known p-type transition metal oxide semiconductor material, which has already been employed in the fabrication of electronic devices. For example Cu2O has been used in thin photovoltaic devices, resistive switching, transistors, gas sensors or catalysts. The films were fabricated by Pulsed Laser Deposition from CuO ceramic target by means of Nd:YAG laser operated at 266 nm wavelength. MgO(100) substrates were mounted on substrate holder 5 cm away from the target and maintained at temperature in the range 500-700 °C. Our attention was mainly focused on the influence of the oxygen pressure, which was varied between 10-5 Pa and 1 Pa, on the structural and following on optical and electrical properties. The investigation of the plasma was carried out by Optical emission spectroscopy. The surface morphology and composition were characterised by AFM and XPS, respectively. The crystalline quality of the films were characterised by means of XRD and following by TEM and HRTEM, which confirmed the epitaxial grown of the films in low oxygen pressure up to 0.1 Pa. When the oxygen pressure exceeded 0.1 Pa the growing films started to be polycrystalline and the CuO phase also appeared. Because we focused on utilization of the Cu2O films as gas sensors, the near ambient pressure photoelectron spectroscopy was carried out to investigation of surfaces composition in the presence of gasses and vapours such as ethanol, hydrogen and NO2.

Resume : Generation, transportation and detection of spin in a controlled manner are very important in spintronic devices for efficient switching mechanisms in a magnetic tunnel junction (MTJ) 1,2. The conversion of charge current to spin current is known as spin Hall effect (SHE) and the inverse phenomenon is inverse SHE (ISHE). The detection of spin is usually realized by the ISHE. Spin Hall magnetoresistance (SMR) arises due to the simultaneous effect of SHE and ISHE in a bilayer heterostructures consisting of a ferromagnetic (or ferrimagnetic) insulator (FMI) and a normal metal (NM). Magnetic Proximity Effect (MPE) observed in YIG/Pt complicates the spin transport scenario with additional effects such as Anomalous Hall effect (AHE) which attenuate SMR signal.4,5. Our group has successfully studied Ga: ZnO insertion on Bi: YIG/Pt and observed SMR signals, but the increase in spurious paramagnetic signal hampered the SMR signals with increasing Ga: ZnO thickness6. A solution for this is to employ antiferromagnetic moments, which are quite stable to stray fields and MPE. Recent studies in this direction have proved successful in generating spin current using antiferromagnets NiO/Pt, Cr2O3/W, CuIr and SrMnO3/Pt layers. Recent theories and experiments carried out by various groups to use spin current as a detection method to probe interface magnetism. We have fabricated Antiferromagnetic oxide and metal oxide heterostructures through pulsed laser deposition and demonstrated tunability of SOC and spin relaxation mechanism through transport measurements. Further possibilities of spin transport through these layers were investigated using angle-dependent magnetoresistance measurements (ADMR). We have varied the deposition conditions such that the magnetic interactions changes from antiferromagnetic to ferromagnetic order and we could identify the magnetic behaviour through spin transport studies carried out in this bilayer samples. The spin current generated in SrIrO3 has other higher-order magnetoresistance components along with spin Hall magnetoresistance. This unusual scenario is challenging as it needs to be addressed theoretically. We would be presenting our experimental observations on spin transport studies carried out in these bilayers. References 1. Matthias Althammer et. al., Phys. Rev. B 87, 224401 (2013). 2. T. Kikkawa et. al., Phys. Rev. Lett. 110, 067207 (2013). 3. E. Saitoh et. al., Appl. Phys. Lett. 88, 182509 (2006). 4. H. Nakayama et al., Phys. Rev. Lett. 110, 206601 (2013). 5. V. Castel et al., Appl. Phys. Lett. 101, 132414 (2012).

Resume : Harvesting energy from temperature gradient between human body and its environment is an attracting and challenging goal. An alternative to Bi2Te3 alloys, the room temperature best performing but toxic thermoelectric (TE) materials, have to be considered while a good skin contact necessitate a flexible TE material. We propose to use health compatible perovskite oxide TE films deposited on a flexible porous silicon (PSi) membrane to fulfill these requirements. Porosification of a Si wafer top surface is obtained by electrochemical etching. A 0.03 mm thick PSi layer can then be peeled-off to get a self-supporting membrane. The idea is to peel-off the membrane after TE generator micro-processing completion, thereby ensuring high temperature mechanical stability for perovskite crystallization and cleanroom handling easiness. We report here on the synthesis and characterization of TE thin film libraries grown by combinatorial pulsed laser deposition. Polycristalline or epitaxial films of (Nb,La):SrTiO3 and (Sr,Ba):LaCoO3 semiconducting compounds (n and p type) are deposited on PSi/Si or single crystal perovskite substrate. Local measurements of the Seebeck coefficient, the electrical conductivity and the thermal conductivity (on Psi) allows for the estimation of the figure of merit ZT across the combinatorial libraries. Doping levels are characterized by XPS and WDX. The evolution of the TE properties versus doping and microstructure will be discussed.

Resume : Yttrium oxide (Y2O3) thin films have been studied previously for different applications, but only recently [Kaminaga et al., 2016] yttrium monoxide (YO) was discovered, by pulsed laser deposition technique, in the form of thin film with a rock salt structure and Y2+ (4d1) valence. The films have narrow optical bad gap ≈ 0.5 eV and electrical conductivity close to metallic state. In this research yttrium oxide thin films with different stoichiometry (YOx) were obtained by reactive DC magnetron sputtering and HiPIMS in an Ar + O2 atmosphere ( ≈ 3 mTorr working pressure) onto different substrates. The O2 partial pressure is varied from 10-7 to 10-5 Torr. The oxygen inlet position is intentionally kept away from the target to sputter in the so called metallic mode. The electronic properties and atomic structures were studied by in-lab techniques such as XRD, XPS (UPS), Ellipsometry, Raman and FT-IR Spectroscopies. The different valance states of yttrium (Y0, Y2+,Y3+) are observed corresponding to the different phases of yttrium oxides (i.e. YO, Y2O3). The oxidation mechanism of metallic Y film is being investigated. Aknowlegment: This research is being suported by the project ERAF No: 1.1.1.1/18/A/073 and ISSP within the scope of young scientific supporting project No :SJZ/2018/12.

Resume : We report on biological-derived hydroxyapatite (of animal bones origin) doped with lithium carbonate (LiC) and phosphate (LiP) coatings synthesized by Pulsed Laser Deposition (PLD) onto 3D Titanium (Ti) implants for biomedical applications. After being validated by in vitro cytotoxicity tests, the Ti implants functionalized with LiC and LiP structures were investigated in vivo, by insertion in rabbit tibia. The in vivo experimental model for testing the extraction force of 3D metallic implants was used. After different periods of time (four and eight weeks), the implants were mechanically removed from the bones and the inferred values were compared with the ones corresponding to bare (control) Ti implants. For both periods, the obtained results were significantly improved, the bone – implant interaction force being more than 25% higher for the functionalized Ti implants in comparison with the simple Ti ones. This is the first report in the dedicated literature on in vivo preliminary assessment of LiC and LiP coatings synthesized by PLD. Along with their low fabrication costs from natural, sustainable resources, these improved mechanical characteristics could offer guidance towards the suitability of using lithium-doped biological-derived materials as viable substitutes of synthetic HA for the fabrication of a new generation of metallic implant coatings. Acknowledgements: Contract PD 6/2018 and Core Programme 16N/2019.

Resume : It is already well known that pulsed laser deposition (PLD) processes foreshadow industrial applications that use magnetron sputtering for thin layer deposition and in particular High Power Impulse Magnetron Sputtering (HiPIMS) systems that ensure a good ionization of the pulverised vapours [1]. Hybrid systems, that simultaneously use PLD processes as well as magnetron pulverisation, are already being implemented [2]. A major problem with HIPIMS and PLD hybrid systems is the deposition of the vapours of the energetic plasma on the access window. We propose a method of realizing a hybrid system HIPIMS + PLD in which the windows are protected by magnetic fields similar to the methods presented in [3]. Thus by using such hybrid system proprieties of thin layer could be improved. 1. K. Sarakinos, J.Alami, S. Konstabtinidis, Surf. Coat. Techn. 204. (1661) 2010 2. Benetti, D., Nouar, R., Nechache, R. et al. Sci Rep 7, (2503) 2017 3 . A. Anders, IEEE Trans. Plasma Sci, 30 (108) 2002

Resume : We report on the deposition of polycrystalline nickel thin films by dcMS and HiPIMS as the tilt angle with respect to the substrate normal is varied from 0 to 70 degrees. The HiPIMS deposited films are always denser, with a smoother surface and are magnetically softer than dcMS deposited films for otherwise the same deposition conditions. The obliquely deposited HiPIMS film is significantly more uniform in terms of thickness. The cross-sectional SEM images reveal that the dcMS deposited film under 70 degrees tilt angle consists of well defined inclined columnar grains while grains of HiPIMS deposited films are smaller and less tilted. Both deposition methods result in in-plane isotropic magnetic behavior at small tilt angles while larger tilt angles result in uniaxial magnetic anisotropy. The transition tilt angle from isotropic to uniaxial anisotropy varies with the deposition method and is measured around 35 degrees for dcMS and 60 degrees for HiPIMS.

Resume : The deposition of calcium phosphate compounds as coatings on metallic or polymeric substrates are of interest for biomedical applications for substitution or regeneration of bones [1]. In radio frequency magnetron sputtering discharges are currently generated, on different type of substrates, such bioceramic layers with optimal adhesion properties either using pretreatment methods or interlayers. Our previous results [2] showed that the thermal patterning of the polymeric substrate during the rf magnetron plasma deposition process of calcium phosphate assured a good adherence of the deposited layers. By switching the plasma at each ten minutes, the temperature at the polymeric substrate didn?t exceed 100 0C. In this work the influence of the cooling of the polymeric substrate on the physicochemical and morphological features of calcium phosphate layers will be analysed. Measurements on the adhesion of the coatings generated on both metallic and polymeric substrates will be performed. References: [1] Surmenev R., Vladescu A., Surmeneva M., Ivanova A., Braic M., Grubova I., Cotrut C. M., Radio Frequency Magnetron Sputter Deposition as a Tool for Surface Modification of Medical Implants, in Modern Technologies for Creating the Thin-film Systems and Coatings, InTech, 2017, 1-36. [2] A. Groza, D. B. Dreghici, M. Ganciu, Calcium Phosphate Layers Deposited on Thermal Sensitive Polymer Substrates in Radio Frequency Magnetron Plasma Discharge, Coatings, 2019, 9, 709.

Resume : Complexity of the chemical structure of polymers, especially copolymers, is an essential matter in the case of the thin film creation by the PVD techniques. Depending on the nature of the physical interactions and the process conditions used, due to the heteroatoms present in the polymer chains, some recombination and/or degradation reactions can occur. The consequent structure alterations can also imply a more complex mechanism of the polymer chains’ transfer during vaporization, sputtering or ablation process, than previously has been thought. Therefore, the aim of our work was to obtain EVA (poly(ethylene-co-vinyl acetate)) thin films using various physical methods, such as PLD, PED, MS and MAPLE, and evaluate their utility in terms of preservation of the copolymer chemical structure. The structure of the films was analyzed using IR and XPS spectroscopy. The morphology of the films was evaluated by SEM and AFM methods.

Resume : For many technological sectors, there is an ever increasing need for thin film deposition processes at low temperature which employs sensitive substrate materials like in flexible electronics, flexible packaging or for protective coatings of polymers. In the case of diamond-like carbons (DLC), pulsed plasmas offer valuable opportunities to obtain highly energetic conditions to grow hard films at viable low deposition temperature. In this work, DLC films were grown both by RF sputtering in Ar-H2 and by plasma-assisted chemical vapor deposition in CH4-CO2. In the first case, pulsing was employed by modulating the RF power applied to the target with frequencies in the range (1-100 kHz) while in the latter case a bi-polar biasing (+/-) was applied to the substrates. The films were characterized for their chemical, structural, optical and mechanical properties in relation with the pulsing conditions. Plasma ion population was determined by means of Langmuir probe diagnostics. Improved film hardness and density together with reduced structural defects were observed with respect to the continuous RF wave or to the continuous negative bias voltage conditions. Strong correlations were found between, on one hand, the plasma ion-population composition changes upon pulsing or the energetic conditions at the substrate upon pulsed biasing and, on the other hand, the film properties modification.

Resume : Smart nano-multifunctional oxide heterostructures such as VO2 have attracted a huge R&D interest because of their ultrafast sharp metal insulating transition (MIT) with a significant change in the electrical resistance making them excellent candidates for a variety of next generation novel optoelectronic nanotechnology applications including femtosecond sensors, gas sensors, smart windows, energy-efficient buildings and information storage memories. A series of high quality VO2 thin film nanostructures were successfully grown on both Al2O3 single crystal substrates and RuO2 conducting oxide thin film buffered Al2O3 substrates using a Pulsed Laser Deposition (PLD) system. Transport measurements of the VO2 epitaxial thin films on Al2O3 substrates as a function of temperature showed a femtosecond sharp 1st order MIT phase transition with a significant decrease in the electrical resistance up to 4 orders of magnitude at a transition temperature of 68 +/- 3 Co. Conducting mapping of the MIT phase transition in the VO2 thin films at different temperatures using AFM technique was investigated. Moreover, theoretical calculations of the VO2 thin films grown on RuO2 buffered Al2O3 substrates could successfully and perfectly recover the 1st order sharp MIT phase transition with significant change in resistivity as in bulk of the VO2 regardless the conducting oxide thin film underneath it.

Resume : Bismuth Ferrite (BiFeO3 or BFO) is a perovskite oxide that have received enormous attention due to many reasons. First, it is considered as the unique room temperature multiferroic exhibiting a robust ferroelectric order (Tc=640K) and an antiferromagnetic state (TN=640K). In addition, in bulk and thin film, BFO shows a high spontaneous polarisation and a cross coupling with magnetic order made of this oxide a promising candidate for future Lead-free magnetoelectric memories. Moreover, nanostructures such as superlattices have become a platform to functionalize novel physical properties driven by the upgrade of layer by layer film growth technology. For instance, BiFeO3/LaFeO3 superlattices (SL) have been studied by Carcan and al. an antiferroelectric-like state has been observed which is generated by strain and symmetry mismatch. Similar to this strategy and using Neodymium Ferrite (NdFeO3 or NFO), we have grown different BFO/NFO SLs by pulsed laser deposition. Due to the smaller ionic size of Nd, different polar behavior is expected comapred to BFO/LFO SLs. The elaboration procedure will be presented with details about the growth control using different techniques. Strain, thickness and periodicity dependance of the SLs are investigated by X-Ray diffraction, Raman spectroscopy, PFM and TEM.

Resume : Within the ByAxon European project (http://www.byaxon-project.eu/), our objective is to develop sensitive magnetic sensors based on the Anisotropic MagnetoResistance (AMR) effects in La_(2/3)Sr_(1/3)MnO_(3) (LSMO) thin films in order to magnetically read the activity of neurons. It is targeted to reach detectivity, defined as the ratio of the electrical noise to the magnetic sensitivity, below nT.Hz^(-1/2) at 310 K (human body temperature) in a frequency range compatible with the electrical activities of neurons (20 - 500 Hz). AMR depends on the angle between the direction of the electrical current and that of the magnetization. It is therefore important to control the magnetic anisotropy in LSMO thin films, and in particular to achieve a uniaxial magnetic anisotropy, with a relatively low anisotropy field, named Ha, while keeping a very low electrical noise. This paper will present a summary of our results on laser deposited LSMO thin films : (1) how to induce uniaxial magnetic anisotropy in LSMO thin films on SrTiO_3 (001) and vicinal SrTiO_3 (001) substrates; (2) how to reduce Ha in order to decrease the detectivity by varying the deposition temperature, film thickness or vicinal angle. Finally, AMR and electrical noise measurements will be presented. Detectivity in the white noise frequency range as low as 100 pT.Hz^(-1/2) could be achieved using 15 nm thick LSMO films on STO (001), and 200 pT.Hz^(-1/2) using 30 nm thick LSMO films on 4° vicinal STO (001) substrates.

Resume : Colossal magnetoresistance La0.66Sr0.33MnO3 (LSMO) thin films have been grown by pulsed laser deposition on SrTiO3 using combinatorial substrate epitaxy (CSE) approach. These polycrystalline substrates have been synthesized by spark plasma sintering (SPS) and polished in order to obtain mirror surface. They present micrometer-size grains with different crystallographic orientations where each grain acts as a single crystal to promote local epitaxy with all the different crystallographic orientations in only one sample. The size of the crystallographic domains can be controlled from 2 to 40 µm depending of annealing temperature during synthesis by SPS. A complete study of grain size, orientation, local epitaxy, and morphology have been investigated by electron backscatter diffraction (EBSD) and atomic force microscopy (AFM) measurements. The study of the magnetic and transport properties shows an increase of the Curie temperature of the LSMO films deposited onto polycrystalline substrates, compare to films deposited on single-crystal SrTiO3 substrate. We show that magnetotransport is strongly affected by CSE approach depending on the crystallographic domain size. A constant high magnetoresistance (MR) appears in the CSE approach from 5 to 320K compare to single-crystal We have also evidenced the apparition of a low field magnetoresistance (LFMR) below 200K. This effect is strongly reinforced by the shrinking of the size domain, related to the presence of the grain boundaries. Finally, we study hysteretic magnetotransport which is also sensitive to domain size and anisotropy. CSE approach is therefore a new way to tune the magnetotransport of complex oxides. Thanks to the PolyNASH project ANR-17-CE08-0012.

Resume : Synthesis of single crystal complex oxide ferroelectric thin films by pulsed laser deposition has been studied for many decades. However, due to interfacial chemistry mismatch, their integration with silicon and nonconventional platforms such as polymer, has remained a holy grail for the research community. We have developed a Layer Transfer Tecnique,[1] which allows us to monolithically integrate these functional materials up to unit cell thickness with silicon and other substrates on-demand. We have demonstrated field effect transistor and tunneling memory devices [2] with large on/off ratio using transferred PbZr0.2Ti0.8O3 films.[1-3] These works provide indication that in future, such trasfer technique can bring complex oxides to the field of microelectronics, a long-cherished goal of the research community. Detailed local electronic transport and structural measurements have revealed new mesoscopic physics in freestanding complex oxide ferroelectric materials such as the presence of strong flexoelectric effects and slow domain wall motion. [4] In this talk, I will provide an overview of our works in this field and discuss physics and device aspects related to freestanding complex oxide ferroelectric materials. References: [1] S. R. Bakaul et al., Nat. Commun. 7, 10547 (2016). [2] S. R. Bakaul et al, Adv. Mater. 29, 1605699 (2017). [3] M. Abuwasib et al., Appl. Phys. Lett. 116, 032902 (2020). [4] S. R. Bakaul et al., Adv. Mater. 1907036 (2019).

Resume : Multiferroic heterostructures of ferroelectric (FE) and ferromagnetic (FM) oxides have potential applications in spintronics, multiferroics and multicalorics [1]. Pulsed laser deposition (PLD) is challenging for the stoichiometric growth of multiferroic heterostructures. We address the key challenges in the PLD of epitaxial thin films of FE oxides of PZT with the FM oxides of LSMO and CoFe2O4 (CFO). Epitaxial PZT/CFO/LSMO heterostructures with ultrathin (10–20 nm) CFO sandwich-layers grown on SrTiO3 (100) substrates exhibited simultaneous improvements of their ferroic properties [2]. Structural analyses using XRD, AFM and TEM revealed their epitaxial growth, smooth surfaces and atomically sharp interfaces. The enhanced magnetization in the samples was associated with the tetragonal distortion of the CFO lattice under epitaxial strain, while trapped charges at the interfaces resulted in their enhanced polarization. Ultrathin (~5-20 nm) epitaxial CFO/LSMO heterostructures grown on MgO (100) substrates exhibited giant magnetocaloric effects. An interfacial strain-induced magneto-structural coupling of the CFO and LSMO layers result in large magnetic entropy changes in these systems. Our work highlights the advances in PLD techniques for the growth of multiferroic heterostructures. [1] A. Barman et al., Adv. Mater. Interfaces 6, 1900291 (2019) [2] D. Mukherjee et al., PRB 95, 174304 (2017); PRB 91, 054419 (2015)

Resume : Pulsed Laser Deposition (PLD) is one of the most widely used deposition methods for thin films at the research and demonstrator development level. Over the past 30 years, the author contributed to establish a highly flexible PLD infrastructure with currently three LPX PRO 305 excimer lasers and in total 8 deposition chambers, most of them suitable for off-axis large-area deposition with extended target-to-substrate distance [1]. Recent advances of the Leipzig group include: (a) Precise implementation of a shadow-mask technique (eclipse-PLD) for considerable improvement of the interface quality of multilayer heterostructures [2]; (b) Various combinatorial techniques with laterally segmented targets to grow lateral or vertical composition spreads on one and the same sample [2]; and (c) Films of challenging materials systems such as copper iodide. CuI is a promising multifunctional transparent p-type semiconductor and subject of the newly established research unit FOR 2857. [1] M. Lorenz, Pulsed Laser Deposition, in Encyclopedia of Applied Physics, Wiley VCH, Weinheim, 2019, eap810. https://doi.org/10.1002/3527600434.eap810 [2] see (a) S. Hohenberger, M. Lorenz et al.; (b) H. von Wenckstern, M. Kneiß, M. Grundmann et al., physica status solidi (b), Special Issue “Functionality of Oxide Interfaces” (2020), published online.

Resume : Metal/Perovskite ferroelectric/metal (M/FE/M) varactors are used in microwave communications. The emergence of 5G communication standards requires to thin down the FE layer making two interface related limitations more prominent: the existence of an interface FE dead layer, and a high leakage current due to insufficient Schottky barrier height (SBH). DFT calculations have shown that the chemical bounding at M/FE interface plays a major role on both SBH and polarization stabilization. In addition to chemical bounding, using a perovskite magnetic electrode offers new leverage with interface properties. Indeed the continuity of the perovskite structure through the interface and its ionic character promotes interplays between charge, orbital, spin and lattice degrees of freedom. We propose here to modulate both the chemical bonding and the polar discontinuity at a La0.7Sr0.3MnO3 (LSMO) / SrTiO3 (STO) epitaxial interface with the insertion of a continuous spread La1-xSrxMnO3 layer (3ML, 0

Resume : The development of physical deposition methods such as pulsed laser deposition and oxide molecular beam epitaxy with in-situ characterisation method have allowed to expand this concept to transition metal oxides. Using layer-by-layer growth, it is possible to engineer new oxide heterostructures and harness the flexibility of design that they offer with their strong electronic correlations, with spin, orbital and charge degrees of freedom, combined with access to new symmetries and electronic band structures. Compared to conventional semiconductor heterostructures, oxides are in its infancy and most of the work has focused on combining compounds with the same structure (perovskite) or with a similar stacking sequence. In this case, dimensional lattice matching is the primary tool to tune the functionality and quality of the growth. Combining materials with different crystal structures, in particular with a radically different stacking sequence has been more challenging. We have shown experimentally that it is possible to produce a coherent interface between a fluorite layer and a perovskite substrate with sustained layer-by-layer growth using pulsed laser deposition. We have carried out comprehensive imaging and analysis of the interface structure and proposed experiments to address to remaining questions on exact cation composition and experimental observation of a changed chemical environment at the interface, provided an atomistic model that is consistent with the four crystal chemistry aspects of the interface structure. Using these information, we have designed a protocol for layer-by-layer growth of defect-fluorite materials on perovskites which involves both lattice and chemical matching.

Resume : The functional properties of complex transition metal oxides are strongly influenced by the elemental composition and the lattice disorder. Although device materials typically require unparalleled levels of purity and perfection, the presence of point and extended defects in oxides have been identified to be advantageous for a variety of applications. Therefore, the precise control over the defect configuration is one of the key challenges for the oxide thin film growth community. Defect formation during pulsed laser deposition growth can be either governed by the defect equilibria at the given growth conditions or by the plume dynamics, the presence of UV-irradiation or by the growth kinetics. We will present detailed studies on selected prototypical oxide thin film systems which enabled us to disentangle the different factors influencing the formation of both, oxygen and cation vacancies. We observe a significant influence of the surface termination of SrTiO3 single crystal substrates on the formation of oxygen vacancies during annealing and growth and attribute it to the inhibited surface exchange for SrO-terminated SrTiO3. By investigating the early stage of growth by in situ AFM and RHEED we could reveal the complex interplay between non-stoichiometry, growth mode and the formation of extended defects such as antiphase boundaries and Ruddlesden-Popper-type of defects. We will furthermore give examples how defect engineering can be employed to fabricate thin film heterostructures and devices with tailored functional properties.

Resume : With the advent of various thin-film deposition techniques, pulsed laser deposition (PLD) has been very successful in synthesizing many oxide thin-films even though it is considered a thermodynamically non-equilibrium process. In this talk, I will discuss the recent progress of the synthesis of epitaxial iridate (i.e., complex iridium oxides) thin-films and heterostructures using PLD with real-time monitoring of in-situ optical spectroscopic ellipsometry. First, I will discuss epitaxial-stabilization strategies to effectively synthesize thermodynamically metastable phases such as Ca2IrO4 and Ba2IrO4 thin films. Second, I will introduce a new approach of synthesizing dimensionally-confined heterostructures, of which dimensionality can be tuned between 1D and 2D. This talk will also present a substantial amount of experimental data regarding structural, optical, electronic, and magnetic characterizations such as optical spectroscopy, Raman spectroscopy, SQUID, and resonant inelastic and elastic x-ray scattering.

Resume : Complex oxides, in particular, perovskite transition metal oxides (TMOs) are of interest to replace conventional semiconductors, because of the possibility to use spin, orbital and lattice degrees of freedom, next to conventional charge manipulation. Where band bending at the interfaces between semiconductors is well understood, the same procedure cannot be applied to TMOs. This limits our understanding on how heteroepitaxy affects the performance of the individual layers. Therefore, the charge transfer at the interface between TMOs has been investigated using the LaCoO3 – LaTiO3 interface. Samples with various combinations of LaCoO3 and LaTiO3 have been fabricated using Reflection High-Energy Electron Diffraction (RHEED) assisted Pulsed Laser Deposition (PLD). Subsequently, the valence of Co and Ti was determined using various spectroscopy techniques. By systematically varying the thickness and controlling all aspects of the fabrication process, significant interfacial charge transfer could be observed. Moreover, introducing a 2u.c. LaAlO3 layer in between LaCoO3 and LaTiO3 severely reduced the charge transfer, providing an efficient way to block these effects. Without a proper structure evaluation, other valence-changing effects cannot be ruled out, therefore correct perovskite structure of these ultra-thin layers was verified using Scanning Transmission Electron Microscopy.

Resume : Ni-base alloys are used in advanced high-temperature (high-T) applications. These alloys contain sufficient Cr to provide a protective Cr2O3 scale in oxidizing atmospheres up to ~900°C. The chromia scale, however, is unstable in high-T service environments containing water vapors. Moreover, above 900°C, evaporation of CrO3 from the surface occurs. Ni-base alloys also contain Al (less than 6 wt.%), which is insufficient for the growth of a protective Al2O3 (alumina) scale. In this work we used plasma immersion ion implantation of fluorine (PIII of F) into Ni-base alloys to facilitate the growth of a protective alumina scale during high-T oxidation exposure while relying on the so-called fluorine effect. The latter involves selective formation of gaseous aluminum fluorides and their subsequent oxidation to Al2O3 close to the surface. Mixtures of either CH2F2/Ar or SiF4/Ar were employed as the precursor F-containing gas. F-implanted samples were characterized by Elastic recoil detection analysis (ERDA) and Particle induced gamma-ray/X-ray emission (PIGE/PIXE). Optimization of the PIII process was done in terms of both the F-containing gas/Ar ratio and the pulse number (implant time). Oxidation kinetics were determined by thermogravimetric analysis (TGA) in laboratory air at 900° and 1000°C for 120 h. Specifically, after PIII of 2×106 pulses (33 min) and subsequent high-T exposure at 900°C, formation of a thin local outer layer of Al2O3 was established in the near-surface region of a Haynes 214 alloy.

Resume : CaVO3 and SrVO3 are newly discovered transparent conductors, belonging to the group of perovskite oxides with strong electronic correlations [1]. This group of oxides offers also an important interplay between the structure of the material and the transport properties, having its impact on the optical properties through the modification of the charge carrier effective mass [2]. The technological potential of these new transparent conductors is largely related to the possibility of integrating vanadates on low cost substrates and especially on glass. In its amorphous form, vanadates are not conducting [3], imposing a growth approach keeping the crystalline character of the material. In this work, we show that by the use of Ca2Nb3O10- nanosheets seed layer prepared by exfoliation process of KCa2Nb3O10 powder and deposited onto glass substrate using the Langmuir-Blodgett method, it is possible to integrate crystalline CaVO3 and SrVO3 thin films by pulsed laser deposition. The growth temperature was investigated and we demonstrate the possibility to grow the films on nanosheets at a moderate temperature required for the integration on glass. We illustrate that their functional properties are competing with the best transparent conducting oxides known so far. This work was supported by the French Agence Nationale de la Recherche (ANR) (ANR-17-CE08-0012) in the framework of the POLYNASH project. [1] L. Zhang et al., Nature Materials 2015, 15, 204. [2] A. Boileau et al., Advanced Optical Materials 2019, 7, 1801516. [3] A. Boileau et al., Appl. Phys. Lett. 2018, 112, 021905.

Resume : Zinc oxide (ZnO) and Al-doped zinc oxide (AZO) are widely used as n-type semiconductor and transparent electrodes in solar cells. Cuprous oxide (Cu2O) is a direct-gap semiconductor with a band gap energy of 2.1 eV [2] also used as absorber in solar cells. High Impulse Magnetron Sputtering allows depositing highly conductive and transparent films on large surfaces and at low temperature [1]. Atomic Layer Deposition (ALD) is used for depositing high quality films with excellent surface coverage. Here we report on the optimization of AZO layers synthesized by reactive HiPIMS [1] as well as on the fabrication of devices based on p-Cu2O/n-ZnO nanojunctions by using a combination of sputtering and selective area ALD [3,4]. Finally, we propose a strategy towards the fabrication of segmented textured solar cells based on such junctions. [1] S. Masudy-Panah, S. Zhuk, H. R. Tan, X. Gong, et G. K. Dalapati, Nano Energy, vol. 46, p. 158‑167, 2018. [2] M. Mickan, U. Helmersson, H. Rinnert, J. Ghanbaja, D. Muller, et D. Horwat, Solar Energy Materials and Solar Cells, vol. 157, p. 742‑749, 2016. [3] C. de Melo et al., ACS Applied Materials & Interfaces, vol. 10, no 43, p. 37671‑37678, 2018. [4] C. de Melo et al., ACS Applied Nano Materials & Interfaces, Vol. 2, p. 4358−4366, 2019

Resume : The aluminium-doped zinc oxide (AZO) may have comparable electrical and optical properties to more expensive Indium-tin oxide (ITO), which is mostly used material for transparent conductive electrodes. Nevertheless, it is difficult to obtain suitable conductivity at low deposition temperatures as the best electrical properties are obtained at 300°C [1]. The reactive high-power impulse magnetron sputtering (HiPIMS) at room temperature was used for preparation of AZO thin film at room temperature. Our research was mainly focused on the possibility to control oxygen content in the deposited AZO films by pulse-averaged target power density [2]. It reveals that an increasing pulse-averaged target power density results in a lower concentration of oxygen in the film due to an increasing predominance of Zn atom and especially Zn ion fluxes onto the substrate. Oxygen content strongly influences the formation of intrinsic defects and thus carrier concentration. Electron microscopy was used to investigate of the film structure, which influences carrier mobility. In case of AZO, It is important to achieve a well crystalline phase. Obtained results imply the benefits of the reactive high-power impulse magnetron sputtering for a high-rate deposition of transparent conductive layers onto heat-sensitive substrates. [1] P. Novák, Phys. Status Solidi. (2019) pssa.201800814. [2] J. Rezek, P. Novák, J. Houška, A.D. Pajdarová, T. Kozák, Thin Solid Films. 679 (2019) 35–41.

Resume : Oxide heterostructures system for photovoltaic applications A. Cheikh (1), A. David (1), U. Lüders (1), C. Labbé (2), J. Cardin (2), D. Kumar (1), A. Pautrat (1), W. Prellier (1) and A. Fouchet (1) (1) NORMANDIE UNIV, ENSICAEN, UNICAEN, CNRS, CRISMAT, 14000 CAEN, France. (2) CIMAP, Normandie Université, ENSICAEN, UNICAEN, CNRS, 14050 Caen Cedex 4,France. Nowadays, looking for light absorbing materials based on perovskite with high chemical stability has recently taken much interest for developing photovoltaic devices [1]. One way of research has recently started on polar heterostructures (similar to LaAlO3/SrTiO3 interface) engineering based on transition metal with different band gap. The use of polar heterostructures lead to (i) a conductive interface and (ii) an internal electric field in the polar material, which is predicted to efficiently separate the photogenerated electron-hole pairs [2]. In order to match with the solar spectrum, it was proposed to substitute LaAlO3 by LaVO3 due to its band gap of around 1.1 eV, which is similar to silicon (1.12 eV). This heterostructure engineering offers the possibility to combine LVO with other oxide with larger band gap such as LaFeO3 (LFO) to improve the absorption at high energy [3]. The main purpose of this work is the deposition and the investigation of the physical properties of (𝐿𝑎𝐹𝑒𝑂3)/ (𝐿𝑎𝑉𝑂3)// 𝑆𝑟𝑇𝑖𝑂3 heterostructure. Both materials LVO and LFO were synthetized as thin films by pulsed laser deposition on STO substrate. The LFO/LVO//STO heterostructures growth conditions were fixed at TG= 600 °C and low oxygen pressure PG = 10-6 mbar. The XRD measurements performed on the heterostructures reveal the crystallization of both materials showing that LFO is perfectly grown on LVO. Nevertheless, the resistance at the STO interface tends to increase with the presence of LFO on top of the heterostructures. In order to overcome this problem, we also prepare some heterostructure with SrVO3 (SVO) as bottom electrode, known as a transparent conductor oxide [4] [5]. Also, from optical point of view, the experimental band gap of LVO and LFO are around 1.4 and 2.2 eV respectively, showing a band gap graded design. Interestingly, optical transitions shift toward low energies with increasing LFO thickness impacting the optical absorption of the heterostructure. As a conclusion from electrical and optical measurements of the heterostructure, by adjusting the thickness of LFO, we are able to tune the electrical behavior and the different optical transitions of the system. Tuning these parameters have a great potential for future integration in photovoltaic applications. [1] L. Wang, Y. Li, A. Bera, C. Ma, F. Jin, K. Yuan, W. Yin, A. David, W. Chen, W. Wu, W.Prellier, S. Wei, and T. Wu, Phys. Rev. Applied 3, 064015 (2015). [2] Othomo and hwang, Nature 427, 423 (2004). [3] E. Assmann, P. Blaha, R. Laskowski, K. Held, S. Okamoto and G. Sangiovanni Phys. Rev.Lett. 078701 (2013). [4] A.Boileau, A. Cheikh, A. Fouchet, A. David, R. Escobar-Galindo, C. Labbé, P. Marie, F.Gourbilleau, and U. Lüders, Appl. Phys. Lett. 112, 021905 (2018). [5] A.Boileau, A. Cheikh, A. Fouchet, A. David, C. Labbé, P. Marie, F. Gourbilleau, and U. Lüders, Advanced Optical Materials 7, 1801516 (2019).

Resume : Reduced graphene oxide (rGO) has attracted tremendous interest in the plethora of applications ranging from flexible optoelectronics1-2, energy storage3, sensing4, and very recently as membranes for water purification5-6. Many of these applications require a reproducible, scalable process for the growth of large-area films of high optical and electronic quality. In this work, we report a one-step scalable method for the growth of reduced graphene oxide like (rGO like) thin-film via pulsed laser deposition (PLD). By deploying an appropriate laser beam scanning technique, we can deposit wafer-scale uniform rGO like thin films with ultrasmooth surfaces (roughness < 1 nm). Further, in-situ control of the growth environment during the PLD process allows us to tailor its hybrid sp2-sp3 electronic structure. This enables us to control its intrinsic optoelectronic properties and helps us achieve some of the lowest extinction coefficients and refractive index values (0.358 and 1.715 respectively at 2.236 eV) as compared to chemically grown rGO films. Additionally, the transparency and conductivity metrics of our PLD grown thin films are superior to other p-type rGO films and conducting oxides. Unlike chemical methods, our growth technique is devoid of catalysts and is carried out at lower process temperatures. This would enable the integration of these thin films with a wide range of material heterostructures via direct growth. References 1. Eda, G.; Fanchini, G.; Chhowalla, M., Large-area ultrathin films of reduced graphene oxide as a transparent and flexible electronic material. Nature Nanotechnology 2008, 3, 270. 2. He, Q.; Wu, S.; Gao, S.; Cao, X.; Yin, Z.; Li, H.; Chen, P.; Zhang, H., Transparent, Flexible, All-Reduced Graphene Oxide Thin Film Transistors. ACS Nano 2011, 5 (6), 5038-5044. 3. Zhu, Y.; Murali, S.; Stoller, M. D.; Ganesh, K. J.; Cai, W.; Ferreira, P. J.; Pirkle, A.; Wallace, R. M.; Cychosz, K. A.; Thommes, M.; Su, D.; Stach, E. A.; Ruoff, R. S., Carbon-Based Supercapacitors Produced by Activation of Graphene. Science 2011, 332 (6037), 1537-1541. 4. Fowler, J. D.; Allen, M. J.; Tung, V. C.; Yang, Y.; Kaner, R. B.; Weiller, B. H., Practical Chemical Sensors from Chemically Derived Graphene. ACS Nano 2009, 3 (2), 301-306. 5. Zhou, K. G.; Vasu, K. S.; Cherian, C. T.; Neek-Amal, M.; Zhang, J. C.; Ghorbanfekr-Kalashami, H.; Huang, K.; Marshall, O. P.; Kravets, V. G.; Abraham, J.; Su, Y.; Grigorenko, A. N.; Pratt, A.; Geim, A. K.; Peeters, F. M.; Novoselov, K. S.; Nair, R. R., Electrically controlled water permeation through graphene oxide membranes. Nature 2018, 559 (7713), 236-240. 6. Abraham, J.; Vasu, K. S.; Williams, C. D.; Gopinadhan, K.; Su, Y.; Cherian, C. T.; Dix, J.; Prestat, E.; Haigh, S. J.; Grigorieva, I. V.; Carbone, P.; Geim, A. K.; Nair, R. R., Tunable sieving of ions using graphene oxide membranes. Nature Nanotechnology 2017, 12, 546.

Resume : Reactive high power impulse magnetron sputtering (R-HiPIMS) has been demonstrated as a promising technique for the ZnO:Al (AZO) thin film deposition at room temperature with improved electrical properties as transparent conduction oxide compared to the reactive direct current magnetron sputtering (R-dcMS). However, there are not enough studies about the HiPIMS process using Zn/Al target itself. Additionally, AZO films have not been deposited with the pulse duration times long enough to allow the discharge to develop into the self-sputtering mode. C-V-t characteristics and the time average plasma optical emission spectra were studied as a function of different sputtering parameters, such as frequency, average power, pulse duration time, and oxygen flow rate. AZO films were deposited on glass substrates without intentional heating by R-HiPIMS using 500 μs long pulses. Structural, electrical and optical properties of the AZO films were studied as a function of peak current. Obtained peak power densities are relatively low compared to other metals due to the strong argon gas rarefaction, however, it is possible to increase the peak power density above 0.5 kW/cm2 by increasing the time between pulses or the average power to reach the HiPIMS regime. If the pulse duration time is 500 μs, the sustained self-sputtering discharge can be observed when the peak power density is above 0.3 kW/cm2. The peak current is sensitive to the oxygen content in the sputtering atmosphere so that it can be used as a control parameter for the reactive sputtering. The lowest obtained resistivity of the AZO films is 1.0×10-3 Ωcm with the thickness about 1000 nm and transmittance around 70% in the visible light range. From the XRD measurements, there is the indication of existing zincblende structural phase in the R-HiPIMS deposited AZO films using high oxygen partial pressure. Zubkins, M., et al., Surface and Coatings Technology 369 (2019): 156-164. Financial support provided by ERDF No. 1.1.1.1/18/A/073 project realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged.

Resume : We have been growing thin films of doped garnets and sesquioxides by pulsed laser deposition for application as lasing waveguides for many years, and have developed a range of techniques for tuning their physical properties to optimise their subsequent lasing performance. We will present the realisation of tailored optical waveguide properties based on optimisation of the target stoichiometry, including deliberate over-compensation of selected elemental composition, as well as dynamic tuning of substrate temperature, deposition laser repetition rate and particulate content within the final grown film. For optical waveguides, the important parameters are the waveguide thickness, refractive index, dopant concentration, optical propagation loss and degree of crystal perfection, all of which are under precise control through attention to the growth parameters as listed above. Importantly, we have recently implemented a novel technique of bi-directional target ablation that minimises the generation of particulates and their subsequent inclusion within the grown film. We regard this as a breakthrough in growth of low propagation loss optical waveguides and will describe this principle in detail. Our techniques enable growth rates of up to 25µm per hour for films with refractive index control to better than 10-3, and optical loss approaching 0.1dB per cm. We will also present our latest results for double-clad films with a buried doped lasing core.

Resume : The strain engineering in oxide ferroelectric thin films is considered as a powerful route to control, tune, and enhance the functional properties and also create/induce new exotic properties that do not exist in bulk materials. The most of the experimental and theoretical research on the strain engineering in thin films has been focused on normal ferroelectric and multiferroic systems, but little effort has been addressed to relaxor ferroelectric materials since they are known to present outstanding dielectric and electromechanical properties especially at the morphotropic phase boundary (MPB) in bulk materials. In the present work we aim to study the effect of the misfit strain on the domain structures and functional properties of prototypical oxide Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) relaxor ferroelectric thin films. PMN-PT epitaxial thin films with different compositions near MPB and with different thicknesses have been grown by pulsed laser deposition on different substrates such as SrTiO3 and rare-earth scandate (REScO3) substrates buffered SrRuO3 conductive layer. The growth mode and surface quality of the layers were monitored using in-situ RHEED. High resolution X-ray diffraction, atomic force microscopy and scanning transmission electron microscopy were used to determine micro-structural and domain structure evolution as a function of strain level. The functional properties such as the ferroelectric and the piezoelectric response have been studied locally using piezoresponse force microscopy. Macroscopic electrical properties have been investigated and correlated to the growth conditions, domain structure and strain level in PMN-PT thin films.

Resume : Nanocrystalline LaB6 thin-films were successfully deposited for the first time via femtosecond Pulsed Laser Deposition (fs-PLD) at room temperature and demonstrated as efficient emitters for a new concept hybrid thermionic-thermophotovoltaic (TIPV) converter capable to generate power at high temperature (>1000 K). The TIPV emitter, not only has to efficiently emit electrons into vacuum, but must also emit photons, which are consequently converted by an optically-matched thermo-photovoltaic cell. We carried out an exhaustive study on the effect that deposition parameters (number of laser pulses, repetition rate, pressure, and deposition time) have on chemical and structural composition, crystallinity and surface morphology of the resulting films. Both surface-sensitive and bulk characterization were employed. Furthermore, we investigated optical and electronic properties in an attempt to maximize the work function values and emissivity capability of the material. Carefully tuned deposition parameters allowed for the production of thin films consisting of nanocrystalline LaB6 (10-20 nm grain-size) with an improved spectral emissivity and a competitive work function of 2.6 eV, comparable to that of single-crystal LaB6. The obtained results indicate that fs-PLD offers an innovative method that allows for the fabrication of efficient, large-area, and cheap thermal electron emitters for new-concept conversion modules operating at temperatures close to 2000 K.

Resume : The pulsed laser deposition (PLD) method allows the growth of epitaxial films and offers a large number of parameters that permit the engineering of the strain state, interfaces, and domain arrangement within the material. Epitaxial high-quality ferroelectric films free from defects allow the maximization of the dielectric breakdown strength (DBS) and thus enhancing the recoverable energy density. In this work, we used PLD to grow lead-free BaTiO3 (BT)/BaZrO3 (BZ) superlattices (SLs) composed of alternating thin layers of the ferroelectric BT and the paraelectric BZ materials. By varying the chemical modulation period (between 1.6 and 50 nm), the epitaxial strain and number of interfaces were varied to tune the dielectric, ferroelectric, and energy storage properties. Interestingly, low periods gave rise to high permittivity and slim P–E loops with promising energy storage properties, attributed to the high strain and/or interfaces effect. Besides, a maximum dielectric tunability was obtained for the weakest periods accompanied by an energy storage density of around 5 J/cm3 and an efficiency of 80% at room temperature. The unsaturated P–E loops and the linear behavior of Wrec versus applied electric field make the ferroelectric/paraelectric SLs systems promising materials for high energy storage density capacitors.

Resume : Multiferroic materials such as bismuth ferrite (BiFeO3) exhibit simultaneous presence of ferroelectric, ferromagnetic and ferroelastic properties and are studied due to their wide range of applications such as electronics, photocatalytic or photovoltaic. The strain engineering effects induced by the substrate lattice mismatch on the functional properties of BFO thin films have triggered the interest on the use of BFO in energy generation applications. However, is a challenge to maintain the same level of epitaxial strain present in ultrathin films (<10 nm), in thick films (>30 nm).In this work, we explore the effects of the thickness- dependent doping of BFO epitaxial thin films with rare-earth elements (Y) coupled with the induced epitaxial strain. Doping BFO with Y allows obtaining controlled structural deformations for energy generation applications.This enables the decrease of the band-gap value from 2.76eV for BFO down to 2.1eV for 5% Y-BFO.Thin films of BFO and Y-BFO with varying concentration of Y of 3% and 5% were grown on STON substrates using PLD method in a multitarget configuration.Furthermore, heterostructures were deposited on monocrystalline and conductive substrates to emphasize the effect of the doping gradient on the electrical properties of the thin films.Several analysis were performed, among which PEC studies revealed that response is strongly dependent on the films thickness, with measured current density values up to J ph= 0.8 mA/cm2, at 1.4V vs. RHE.

Resume : Manganese oxide electrodes provide higher energy density than electric double layer capacitors (EDLCs) because of excellent Faradaic redox reactions taking place on or near the electrode surface. To develop thin film electrode materials for the practical application in energy storage devices, a low-cost and high-throughput thin film fabrication technique is desirable. Herein, we describe the fabrication of highly porous three-dimensional nanostructured of manganese oxide-reduced graphitic oxide (MnOx-rGO) electrode in several seconds by using a pulse-photonic processing technique. The nanostructure facilitates the movement of ions/electrons and offers an extremely high surface area for the electrode/electrolyte interaction. The electrochemical performance was investigated by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) with 1 M KOH as the electrolyte. The as-synthesized thin film electrode exhibits excellent electrochemical performance and an ultra-long lifetime by retaining 90% of initial capacitance even after 100,000 GCD cycles at 0.4 mA/cm2 constant areal current density. We attribute this excellent performance to the conductive reduced graphitic oxide and synergistic effect of carbon composite and the metal oxide, and unique porous nanostructure. Such highly porous morphology also enhances the structural stability of the electrode by buffering the volume changes during the redox processes.

Resume : PLD as a deposition technology has the image of a simple process technology with the possibility of creating highly complex films in a simple manner. Based on this picture, it looks easy to create the necessary hardware at the institute level - with a small budget: the va-cuum level is easy to reach, so one existing vacuum chamber could be used for it.... a simple heater could be bought for low price and a target material for the corresponding layer is produced in-house. A laser exist already and needs only "focused" on the target via a window ..... done. Of course you can create layers with it. The problem begins when physical laws are to be examined and evaluated on the basis of these layers. The ability of the process parameters to interpret the layer formation and its properties comes to a quick end when a process delivers poorly reproducible results. The lecture deals with the optical beam path from the laser to the target as well as the target laser interaction and the resulting necessary precautions. The requirements for the type of substrate heating and the target manipulation are described as well as the process feedback on the system components.

Resume : The effects of a positive pulse following a high-power impulse magnetron sputtering (HiPIMS) pulse have shown by several researchers to generate an energetic ion flux towards the substrate which in turn result in better coatings and sometimes in a higher deposition rate as compared to classical HiPIMS. These are intriguing results that promise to be very useful for synthesis of insulating coating or coatings on insulating substrates. The mechanism of ion acceleration is described differently by different researcher. Wu et al. explain the acceleration to occur close to the sputtering target, [1] while other describe a drop in the plasma potential further away from the target, generated by the limited mobility of electrons in between the magnetron trap region and the region closer to the substrate. [2,3] Another possibility is that the whole plasma volume is elevated by the positive pulse and that the ion acceleration occurs only in the sheath at the substrate, as has earlier been described by Nakano et al. [4]. The field is under intensive investigations and the latest results know to the presenter will be described and discussed. [1] B. Wu et al., Vacuum. 150 (2018) 216 [2] I.-L. Velicu et al, Surface & Coatings Technology 359 (2019) 97. [3] J. Keraudy, R.P.B. Viloan, M.A. Raadu, N. Brenning, D. Lundin, U. Helmersson, Surface & Coatings Technology 359 (2019) 433. [4] T. Nakano et al, Vacuum. 87 (2013) 109

Resume : Effects of double columnar structure nano composite film, in which tensile strain were introduced, on cathodic activity of SmCoO3 was investigated. Double columnar film of Pr2NiO4(PNCG)-Sm doped CeO2 (SDC), PrBaCo2O5.5-SDC, Sm0.6Sr0.4CoO3(SSC)- SDC, and La0.6Sr0.4FeO3-SDC were successfully prepared by pulsed laser deposition method and it was found that insertion of PNCG-SDC or SSC-SDC double columnar film decreased the overpotential of SSC cathode significantly. The power density of the cell deposited on Ni-Fe porous metal substrate was higher than 3W/cm2 at 973K and impedance results suggested that the increased power density was explained by decreased cathodic overpotential. Since cathodic activity of double columnar layer was quite poor, increased diffusivity of oxide ion in double columnar film is effective for expanding reaction area resulting in the increased cathodic performance for oxide ion dissociation.

Resume : Abstract Owing to their outstanding novel applications in optoelectronic sensing, smart windows and information storage nanotechnology, smart multifunctional oxide nanostructures including metal insulating transition (MIT) thin films have recently received a great attention. This review is timely and important because there is a need from optoelectronics industry to develop high quality-low cost novel nanodevices coupled with potential opportunities for discovering new multifunctionality and breakthrough. The review discusses thin film deposition and nanofabrication technological techniques of multifunctional complex oxide heterostructures including MIT thin films and nanoparticles. In particular, the advance in thin film and nanoparticles fabrication technology using pulsed laser deposition (PLD), chemical vapour deposition (CVD), plasma enhanced chemical vapour deposition (PECVD) systems are critically reviewed.

Resume : In this work, the effect of the film growth rate, R, on the microstructure and the dc transport properties of high temperature superconducting YBa2Cu3O7-x (YBCO) films with incorporated Ba2(Y/Nb)O6 (BYNO) and Ba2(Y/Ta)O6 (BYTO) secondary phases is reported. Nanocomposite YBCO films are deposited by pulsed laser ablation with the film growth rate changed in the range R = 0.02 – 1.8 nm/s by varying the laser repetition rate. The samples are analyzed by TEM and X-ray diffraction investigations and critical current density measurements in a wide range of temperature (4.2 K < T < 77 K) and magnetic field up to 18 T. Two effective microstructural landscapes have been identified within the investigated R range. At low R, a well-defined BYNO and/or BYTO columnar system, very effective in improving vortex pinning in the high temperature range (77 K), is developed. This contrasts with the fast rate limit (high R) in which secondary phases are assembled within the YBCO film matrix in form of splayed nanorods and meandered columns with a high density of short stacking faults resulting in a more effective pinning at low temperature (4.2 K). These results point the way to yet further improvements of the YBCO properties by further tuning and refining the YBCO nanocomposite growth conditions for applications as large magnets for nuclear fusion reactors and particle accelerators. This work has been partially carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom programme 2014-2018 and 2019-2020 under grant agreement N° 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 823717 – ESTEEM3