Zinc Oxynitride (ZnOxNy) thin films display high mobilities and a considerable tunability of both the free electron concentration and optical band gap. The properties achievable for this material systems makes ZnOxNy an intriguing n-type absorber candidate in silicon-based tandem solar cells. We have studied how the O:N ratio affect structural, optical and electrical properties of magnetron sputtered ZnOxNy thin films, as well the electrical behavior of ZnOxNy-Si pn hetereojunction diodes. X-ray diffraction of the ZnOxNy films indicate either a Zn3N2-like structure or ZnO-like grains in combination with structural disorder. As the O:N ratio is increased, the optical band gap of ZnOxNy films increase from 1.1 to 1.9 eV. Hall effect measurements of the n-type ZnOxNy films show free electron concentrations varying with the O:N ratio, from 9.8×1017 to 1.5×1016 cm−3. Hall mobility up to 88 cm2/Vs is achieved. We observe the formation of pn hetereojunction diodes between ZnOxNy-films and p-Si. The electrical characteristics of these diodes are shown to depend on the ZnOxNy anion compositions. Current rectification of 3.7 orders of magnitude is achieved between -1 and 1 V at room temperature. However, the built in voltage extracted from capacitance-voltage measurements are higher than theory suggest, implying an influence of defects on the electrical characteristics.

The high performance and reliability of low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) on flexible substrates need to be ensured for the proper operation of advanced flexible organic light-emitting diode (OLED) displays. However, due to the heat-sensitive components of flexible LTPS TFTs, their fabrication process faces challenges in the temperature management of its thermal treatment procedures such as activation annealing, which is an essential step in the in-line fabrication process of LTPS TFTs for activating dopants and reducing silicon lattice-related structural defects. In this work, we investigate the optimization of the activation-annealing process through the modulation of its process temperature. As the activation-annealing temperature was increased from 320 °C to 370 °C, the electrical characteristics and reliability of flexible LTPS TFTs improved owing to a decrease in the gate dielectric/channel interface and bulk channel defects. However, as the temperature was further increased to 420 °C, considerable degradations in device performance and reliability were observed due to a significant increase in the deep-level gate dielectric/channel interface and bulk channel defects. Physical analysis revealed that significant dehydrogenation, in which the breakage of Si−H bonds causes excess Si dangling bonds, occurred at 420 °C. This work shows that a fine temperature optimization of the activation annealing process is a necessary procedure for ensuring highly performant and reliable LTPS TFTs on flexible substrates.

Ti2N MXene phase was synthesized by interdiffusion of TiN/Ti multilayers by dc-magnetron sputtering at 698 K. The Atomic force microscopy (AFM) reveals the root mean square (RMS) roughness of the TiN/Ti multilayer was ∼4.78 nm of pristine samples which increased to ∼5.74 nm after annealing. The total thickness of (TiN10 nm/Ti10 nm), (TiN5 nm/Ti5 nm), and (TiN2.5 nm/Ti2.5 nm) multilayers was 200 nm as estimated by X-ray reflectivity (XRR). The secondary ion mass spectroscopy (SIMS) data reveals the diffusivity of N2 in the (TiN/Ti) multilayer is ∼10−18 m2s−1 at 698 K. The X-ray diffraction (XRD) planes of (112), (200), (220), (224) are at 36.95⁰, 42.89⁰, 62.25⁰, and 78.53⁰ 2θ values respectively confirming the Ti2N MXene phase and the X-ray photoelectron spectroscopy (XPS) confirmed Ti(2p) and N(1s) core orbitals are at 457.14 eV and 397.17 eV on the surface of TiN/Ti multilayer thin films. The X-ray absorption spectroscopy (XAS) of N and Ti L-edges were found at 404.51 eV, and 462.38 eV respectively which were shifted towards the right and left respectively after annealing indicating an increase and decrease in the oxidation state. Raman bands TA, LA, and TO were shifted towards higher wave numbers to 238, 337, and 634 cm−1 respectively for annealed TiN/Ti multilayer thin films.

The pulsed laser deposition (PLD) technique is employed in this research to fabricate thin films of Silicon-doped Tin Zinc Oxide (Si-SnZnO3) on a Magnesium Oxide (MgO) substrate. Additionally, Si-SnZnO3 thin films are grown on a Strontium Titanate (SrTiO3 or STO) buffer layer with a thickness of 60 nm, which is deposited on the MgO substrate. The target materials used in the PLD technique, Si-SnZnO3, and SrTiO3, are prepared using the solid-state technique. The current study aims to explore the influence of the STO buffer layer on the ferroelectric behavior of the Si-SnZnO3-grown film. Accordingly, the structure, morphology, and film thickness of Si0.5Sn0.5ZnO3/MgO and Si0.5Sn0.5ZnO3/STO/MgO samples are investigated using X-Ray Diffraction and Scanning Electron Microscope techniques respectively. Furthermore, the uniformity of different film thicknesses grown on STO/MgO is investigated using Atomic Force Microscopy. Both the resistivity and the carrier mobility for Si0.5Sn0.5ZnO3 /MgO sample are 3.22 × 103 Ω.m, and 7.35 × 107 m/(V⋅s) (semiconductor), whereas there are 4.31 × 103 Ω.m, and 63.1 m/(V⋅s) (insulator) for the Si0.5Sn0.5ZnO3/STO/MgO substrates, respectively. The Polarization-Electric Field hysteresis loops of different film thicknesses show Lossy capacitor response and Non-linear ferroelectric response for Si0.5Sn0.5ZnO3/MgO, and Si0.5Sn0.5ZnO3/STO/MgO, correspondingly. Moreover, the ferroelectricity parameters of the Si0.5Sn0.5ZnO3 films deposited on the STO/MgO were improved by an order of magnitude compared to the thin film on the MgO substrate. The obtained results indicate that Si0.5Sn0.5ZnO3/STO/MgO configuration could be suitable for Ferroelectric Random Access Memory applications.

In this study, electric field-enhanced aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) thin films was investigated considering various current densities. Constant electric currents of 4, 5, and 6 A were applied to assess the Joule heating characteristics during specific durations (40, 15.5, and 9 s). The samples were prepared by depositing a 200-nm thick a-Si layer on a glass substrate and sputtering a 300-nm thick aluminum (Al) layer onto the a-Si layer. During the AIC process, layer exchange occured via the diffusion of silicon (Si) into the Al layer. This phenomenon was verified by the in-situ reflectivity, which was in excellent agreement with thin-film optics calculations. During the annealing, processing temperatures were lower than 470 °C, which is less than the Al-Si eutectic temperature of 577 °C. The Raman peak observed near a wavenumber of 519 cm−1 revealed the formation of polycrystalline silicon films through Joule heating processes. Field-effect scanning electron microscopy images were captured and analyzed to investigate the surface morphology of the samples, specifically focusing on grain growth.

Epitaxial 31-nm-thick (001) NiCo2O4 films exhibiting metallic and ferrimagnetic properties at room temperature were grown on (001) MgAl2O4 substrates at various deposition temperatures. θ/2θ scan and reciprocal space mapping X-ray diffraction measurements indicated that tetragonal lattice distortion in the (001) NiCo2O4 films increased with the deposition temperature. Metallic ferrimagnetism and perpendicular magnetic anisotropy (PMA) were observed for (001) NiCo2O4 films grown at deposition temperatures below 350 °C. Remarkably, the ferrimagnetic transition temperature continuously decreased with increasing deposition temperature up to 350 °C, whereas images of the magnetic domains indicated that the density of the nucleated small domains during the early stage of magnetic reversal increased with the deposition temperature. Consequently, the PMA of the (001) NiCo2O4 films at room temperature was optimized using a deposition temperature of approximately 320 °C. The results of this study indicate that the deposition temperature is a useful parameter for adjusting the PMA and magnetic domain structure of NiCo2O4 films by inducing variations in structural distortion and metallic ferrimagnetism.

The triple-layered structure comprising an ultrathin (∼10 nm) Ag layer embedded between two dielectric layers exhibits high visible light transmittance, electrical conductivity, and flexibility, and this triple-layered structure is thus considered as a promising candidate to replace the conventional single-layered indium tin oxide (ITO) transparent conductive electrodes in optoelectronic devices. While various dielectrics have been employed for the underlayer and overlayer, ITO and zinc oxide (ZnO) are the two common choices. In this study, we investigated the structural, electrical, optical, and thermal properties of triple-layered electrodes (dielectric underlayer/Ag/dielectric overlayer) comprising Ag, ZnO, and ITO; namely, ZnO/Ag/ZnO, ZnO/Ag/ITO, ITO/Ag/ITO, and ITO/Ag/ZnO electrodes, in which all layers were sputter-deposited at 293 K. The deposition of crystalline Ag onto crystalline ZnO and amorphous ITO surfaces exhibited distinctly dissimilar Ag nucleation dynamics, resulting in significant differences in the structural and thus electrical characteristics prior to Ag-layer-closure. After the formation of continuous Ag layers, the electrical conductivities became similar, whereas the optimized ITO/Ag/ZnO structure exhibited a considerably higher visible light transmittance than the other electrodes (with an average transmittance of 92.8%). Further, we found that the ZnO/Ag interface stability was significantly higher than that of the ITO/Ag interface during an electrically driven Joule heating process.

Thin film of double perovskite oxide Dy2NiMnO6 (DNMO) has been synthesised by the simple and cost-effective chemical solution deposition technique. The room temperature X-ray diffraction pattern and Raman spectroscopy confirm the monoclinic (space group - P21/n) crystal structure of polycrystalline DNMO thin film. The optical and electrical properties of DNMO thin film are investigated to study the detailed photo physical properties of DNMO thin film. The direct band gap and temperature dependant impedance spectroscopy confirm its semiconductor behaviour. Impedance spectroscopy also shows two types of dielectric relaxation behaviour and the nature of conductivity reveals the electron hopping conduction mechanism. Moreover, the chemical solution deposited DNMO film shows promising photo response under white light.

Orientation, structure and morphology in the early growth stages of CuO films on strontium titanate were studied by synchrotron radiation X-ray diffraction. Nanostructured CuO films were obtained by ex situ heat treatment at 970 K in oxygen flow at ambient pressure after an initial deposition of Cu on SrTiO3(001) at 10−4 Pa oxygen pressure using the molecular beam epitaxy technique. These films at low coverages grow forming islands a few tens of nanometers wide, with the [010] direction perpendicular to the substrate surface. Two types of epitaxies are observed, CuO[001]//SrTiO3[100] and CuO[100]//SrTiO3[100], the former being the preferred one. The combination of these epitaxies with the P4mm surface symmetry of the substrate generates 16 different orientations of nanostructures. The lattice constant values obtained from X-ray diffraction are very close to those of bulk tenorite, with the exception of the monoclinic angle β, which is reduced from 99.54° to 96.76(8)° by the epitaxy constraints. This angle is a key parameter in determining the magnetic properties of CuO.

Femtosecond laser (@1030nm, 280fs) was applied to irradiate SiO2 thin films in the hope of improving damage resistance of films to nanosecond ultraviolet (UV) laser light (@355nm, 4ns). The optical and mechanical properties of laser strengthened SiO2 thin films were characterized and laser-induced damage threshold (LIDT) results show that femtosecond laser irradiation can significantly improve LIDT of the films to nanosecond UV laser light from 5.45J/cm2 to 28.96J/cm2 by a factor of 5. Fluorescence and Fourier Transform Infrared (FTIR) spectra indicate that the LIDT improvement is attributed to the decrease in hydroxyl group's(OH) density in SiO2 thin films resulting from femtosecond laser irradiation.

This study explores the use of Secondary Ion Mass Spectrometry (SIMS) to accurately measure the content of Pb1−xSnxTe, a new class of electronic materials known as Topological Crystalline Insulators (TCIs). We analyzed the SIMS signal ratios of SnCs+/PbCs+ and Sn±/Pb± in thin layers and determined the calibration curves necessary to estimate the exact amount of content in this ternary compound. Additionally, we investigated the matrix effect and performed depth profiling to obtain a more precise determination of the content. These findings contribute to the understanding and development of TCIs, and highlight the potential of SIMS for accurate content determination in ternary compounds.

Multicomponent TiVTaNbZrHf alloy and (TiVTaNbZrHf)N coatings were deposited on Ti6Al4V alloy by High Target Utilization Sputtering. Sputtering was carried out by reactive sputtering from a TiVTaNbZrHf target with a different nitrogen addition. The microstructures, mechanical properties, and cytotoxicity tests were studied. It was found that the (TiVTaNbZrHf)N coatings showed a dense columnar structure with a face-centered-cubic solid solution phase. The (ZrTaNbVHfTi)N with 4 sccm nitrogen addition exhibited the highest hardness of 34 ± 0.33 GPa and high Indentation modulus of 408.47 ± 24.97 GPa. The mechanical properties greatly depended on the amount of added nitrogen in reactive plasma Physical vapor deposition sputtering. Cytotoxicity tests proved that a very high percentage of live cells were observed after 7 days of incubation time on (TiVTaNbZrHf)N coating.

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The visible-light-responsive photocatalytic activity of TiO2 coatings offers a promising route for the antibacterial functionalization of Ti implants. In this study, carbon and nitrogen co-doped single-phase rutile TiO2 films were fabricated on Ti substrates via a two-step thermal oxidation process involving subsequent treatments with N2–1% CO and N2–1% O2. Under optimized treatment conditions, the single-phase rutile TiO2 films exhibited antibacterial activity against Escherichia coli under visible-light irradiation (λ > 400 nm) at 15 mW∙cm–2 for 15 min. The TiO2 films exhibited a double-layered structure comprising an inner layer (containing carbon and nitrogen) on the Ti substrate side and an outer layer (without carbon or nitrogen) on the topmost surface. The excitation of electrons and holes generated by dissolved carbon and nitrogen in the inner layer of the TiO2 films contributed to visible-light responsiveness. The bonding strength between the TiO2 film and Ti substrate exceeded 60 MPa. The cytotoxicity against the mouse osteoblast-like cell (MC3T3-E1) of the TiO2 film was comparable to that of well plates, under visible light and in the dark. This study demonstrates the visible-light-responsive antibacterial activity of a single-phase rutile TiO2 film on Ti. Further, the TiO2 film exhibited excellent bonding strength with the Ti substrate, indicating its high potential as an antibacterial active coating in combination with visible-light irradiation for Ti implants.

Abstract not available

Increasing demand for wearable sensors and heating elements has occurred recently. Herein, graphene has been observed as a biocompatible, cost effective, and multidimensional material catering to both sensing and heating applications. However, it still lacks essential features such as high temperature performance with low power usage, high strength, and robustness of thin films in tough environments such as heating elements in thermal socks. Hence, in this paper, we demonstrated laser induced graphene (LIG) as a suitable candidate for wearable thermal applications. LIG heaters were fabricated using a cost effective and environmentally friendly technique based on photothermal ablation of polyimide substrate using a 50W CO2 laser. The heat flux of LIG heater was improved by stacking multiple films while their electrical connections are made in parallel. Upon joule heating, the heaters had excellent electrothermal performance, fast and stable response, achieving temperature of 195°C using a relatively low DC voltage of 10 V. Most importantly, they showed good durability after bending, washing and repeated heating and cooling cycles. Due to these advantages, the LIG-based thin film heaters have potential as reliable and low-cost heating elements for variety of tough applications such as defrosting and wearable thermal pads.

Combining chemical vapor deposition (CVD) with electrochemical polish (EP) operation is a promising route to producing performance-capable superconducting films for use in the fabrication of cost-effective components for superconducting radiofrequency (SRF) particle accelerators and superconducting quantum computers. The post-deposition EP process enables a critically necessary reduction in surface roughness of niobium (Nb) thin films to promote optimal superconducting surface conditions. This work investigated surface morphology, roughness, and crystal orientation of the CVD-grown and EP-polished Nb films. The CVD films were found to comprise steps and pyramidal features, resulting in undesirable large peak-to-valley distances. EP was demonstrated to significantly diminish the height of pyramids and effectively minimize the overall surface roughness. EP results showed a probable dependence on the crystal orientation. These understandings identify the EP principles tied to CVD-grown Nb films that allow further refinement of surface profiles for film-based SRF applications.

Hybrid thin film sensors based on semiconductor oxides and carbon nanostructures are promising materials to improve the sensing, thermomechanical and optical properties. In this study, a thin film based on a composite from ZnO nanoparticles, milled multiwalled carbon nanotubes, and conducting polymer was fabricated. The layer was spray-coated to the surface of amorphous polyethylene terephthalate substrate. The hybrid layer and components have been systematically characterized by transmission and scanning electron microscopy, dynamic light scattering and the optical absorption spectrum was observed by ultraviolet-visible spectroscopy. The change in glass transition temperature was measured by dynamic mechanical analysis. Gas sensing tests reveal that the ZnO/multiwalled carbon nanotube/ poly(3,4-ethylenedioxythiophene): polystyrene sulfonate film on amorphous polyethylene terephthalate has remarkably enhanced performance compared to the same layer on indium tin oxide /polyethylene terephthalate. It could detect ethanol vapor in a wide concentration range with good response, fast recovery, and repeatability at room temperature. The layer was also tested as an ultraviolet photodetector, showing a promising signal. These features indicate the composite usability in further sensor applications.

Undoped and doped zinc oxide in film form is used in a wide range of applications. Its electrical and optical properties depend on the oxide conditions during preparation, which are influenced by many deposition parameters. The aim of this work was to experimentally investigate the properties of films deposited under clearly defined oxygen-rich and oxygen-poor conditions. The observed property changes were then described based on theoretical assumptions about internal defects formed in ZnO under different oxygen conditions. To achieve the objective, the ZnO and ZnO:Al films were sputtered in a mixture of argon and oxygen to ensure oxygen-rich conditions. Oxygen-poor conditions were provided by co-sputtering from oxide and metal targets in argon. We have found that the growth in oxygen-rich conditions leads to approximately stoichiometric ZnO films and the films prepared under oxygen-poor conditions are strongly oxygen deficient. The resistivity of undoped ZnO films can be controlled from 108 to 10−2 Ωcm while maintaining high transparency in the visible spectrum. The high resistivity is caused by the formation of deep acceptors under oxygen-rich conditions. The high concentration of zinc interstitials is responsible for the low resistivity in oxygen poor conditions. Even in the case of ZnO:Al films, the carrier concentration is strongly reduced at oxygen-rich conditions by the deep acceptors. These defects tend to relax during vacuum annealing at 300 °C due to self-diffusion. The carrier mobility is mainly related to the crystallinity. The formation of a high number of basal edge dislocations has been identified as a reason for the reduction in transmittance.

Magnesium fluoride protected aluminum (MgF2/Al) vacuum ultraviolet (VUV) coatings were prepared by electron-beam evaporation process with excellent controllability. The effects of preparation conditions on the microstructure and VUV reflectivity of MgF2/Al coatings were studied. The experimental results showed that crystalline MgF2 layers were grown at 250 °C and were beneficial to improving the VUV reflectivity of mirrors. However, the temperature rise led to the growth of Al nanowires on the mirror surfaces with relatively thick Al films, and the Al nanowires continued to grow with the extension of baking time. It was found that reducing the thickness of Al film could not only suppress the generation of Al nanowires, but also decrease the surface roughness of mirrors. The negative impacts of Al nanowires on the performance of VUV mirror were analyzed. The physical mechanism of suppressing the generation of Al nanowires was discussed. This work would provide a reference for the growth of VUV grade Al film by electron-beam evaporation, and also valuable experience for the study of thermal stability and surface roughness control of Al-based VUV coatings.