Reactive Sputtering Technique Research Articles

Exploring the synaptic response of reactive Mn electrodes based TiO2 resistive switches

Mn/TiO2/Mn devices, prepared by reactive sputtering and photolithography techniques, were characterized by analyzing their current–voltage (I-V) dependence, non-volatile memory properties, and artificial synapse behavior. The detailed study of its I-V characteristics allowed for highlighting the main conduction mechanisms involved in the electrical transport through the Mn-TiO2 junctions and determining an equivalent circuit model. These results show that the oxidation of metallic Mn electrodes and the application of electrical pulses produce a complex scenario associated with a highly inhomogeneous oxygen vacancy distribution. The resistance hysteresis switching loops were determined, as well as the synaptic-like weight depreciation and potentiation, revealing a linear dependence of the reset voltage as a function of the amplitude of the set voltage and a quasi-linear variation of the conductance with the number of applied pulses. Simulations based on spiking neural network architecture, considering different updates of the synaptic weights, were trained to learn handwriting patterns. Notably, those based on the linear learning rule of the Mn/TiO2/Mn devices outperformed others with increasing non-linear behavior, demonstrating both high recognition and noise tolerance factors, further highlighting the robustness of this approach.

Enhancing the Wear Performance of 316L Stainless Steel with Nb2O5 Coatings Deposited via DC Sputtering at Room Temperature under Varied Environmental Conditions

Niobium-based oxides have garnered increased attention in recent years for their remarkable enhancement of corrosion resistance, as well as biofunctional properties of various metallic materials, including 316L SS. However, the mechanical properties of these promising coatings have not been fully elucidated. This study investigated how much the environmental conditions (air, artificial saliva, and NaCl solution) impact the wear performance of 316L SS without and with Nb2O5 coatings deposited via the reactive sputtering technique. The results exhibited a notable decrease in friction coefficient (55% in air, 18% in artificial saliva, 10% in 0.9 wt% NaCl solution), wear area (46% in air, 36% in AS, 17.5% in 0.9 wt% NaCl solution), and wear rate (44.0% in air, 19.5% in AS, 12.0% in 0.9 wt% NaCl solution). Ultimately, the results obtained in the present study elucidate the synergistic mechanisms of corrosion and wear in 316L SS containing Nb2O5 coatings, highlighting its significant potential for applications in the biomedical sector.

Structural, morphological, and chemical composition of ternary ZrHfN thin films deposited by reactive co-magnetron sputtering

This study focuses on a deposited ternary zirconium hafnium nitride (ZrHfN) thin film prepared using the reactive co-magnetron sputtering technique. The effect of the nitrogen (N2) flow rate on the films' structural, morphological, and chemical composition was investigated. The gracing-incidence X-ray diffraction (GIXRD) showed that all ZrHfN thin films exhibited a crystalline face-centered cubic structure with a strong (111) orientation. With increasing the N2 flow rate, the film's crystallography changed based on thermodynamic theory. The films demonstrated uniformity and homogeneity in their ternary nitride composition, as confirmed by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) mapping and electron probe microanalyzer (EPMA). Chemical state analysis using X-ray photoelectron spectroscopy (XPS) indicated the presence of both nitride and oxynitride species in all samples. Notably, the atomic concentration of the main elements (Zr, Hf, and N) remained relatively stable over the controlled N2 flow rate range. However, the N2 flow rate played a crucial role in forming hafnium nitride and oxynitride chemical states, whereas it did not significantly influence the Zr phases, dominated by Zr oxides. Additionally, the hardness of the ternary ZrHfN thin films exhibited enhancement comparable to typical ternary nitrides.

Photocatalytic activity of TiO2:TiN nanocomposite films prepared by DC reactive sputtering technique for air purification

This study concerns the production of advanced materials and a novel technique for enhancing photocatalytic efficiency, focusing specifically on the purification of air contaminated with methane gas. Titanium dioxide:Titanium nitride (TiO2/TiN) nanocomposite films were prepared by dc reactive magnetron sputtering of highly-pure titanium sheet in presence of oxygen and nitrogen as reactive gases with optimized mixing ratios to produce the composite structures. The structural, morphological, and optical characteristics of the prepared nanocomposites were determined and analyzed. The primary goal of this study was to enhance the photocatalytic activity of such nanocomposites against methane gas pollution. It is observed that increasing the nitrogen content in the TiO2:TiN nanocomposite structure led to notable improvements in photocatalytic efficiency. Specifically, when these nanocomposites were subjected to a UV light, they exhibited enhanced photocatalytic activity in the removal of methane gas from the surrounding air, which demonstrates a direct correlation with increased nitrogen (N) content in the composite structure. These nanocomposites are reasonably promising in removing harmful gases and pollutants present in indoor and outdoor environments. This exploration not only sheds light on the remarkable potential of TiO2:TiN nanocomposites for air purification but also highlights the importance of innovative techniques, such as dc reactive magnetron sputtering in the field of materials science and engineering as well as in environmental remediation.

Synthesis and Characterization of Nickel Ferrite Nanostructures by DC Reactive Sputtering Technique Using New Target Configuration

Synthesis and Characterization of Nickel Ferrite Nanostructures by DC Reactive Sputtering Technique Using New Target Configuration

Epitaxial growth and stoichiometry control of pyrochlore Nd2Ru2O7 thin films

We report on the epitaxial growth of pyrochlore NRO thin films utilizing a reactive off-axis sputtering technique. The growth process employed Ru and Nd metal targets with a repetitive substrate temperature sequence. X-ray diffraction, magnetic susceptibility, and spectroscopic ellipsometry measurements confirm that the structural, magnetic, and electronic properties of near-stoichiometric NRO films match those of the bulk material. Our spin-polarized density functional calculations based on Nd2Ru2O7 structural parameters accurately describe the optical spectra and assign Hubbard bands to the interband transitions observed above the optical band gap of 0.2 eV. By utilizing the technique's capability to adjust the degree of ruthenium deficiency, we investigated Nd2Ru2O7 films across a wide range of stoichiometric variations. Decreasing the Ru/Nd ratio results in lattice expansion, an increase in the optical band gap, and the suppression of Ru 4d intersite optical transitions. Additionally, this adjustment facilitates the elimination of minor inclusions of a ferromagnetic NdOx impurity phase, influencing the magnetic properties of stoichiometric films at low temperatures. The successful growth of Nd2Ru2O7 films opens up promising opportunities for designing and exploring strain- and light-induced states in pyrochlore ruthenates. Published by the American Physical Society 2024

Leveraging oxide reactive sputtering for thermal insulation in laser-heated diamond anvil cell

ABSTRACT We have developed an oxide reactive sputtering technique aiming at rapidly sputtering high-quality oxide films on a diamond surface, providing excellent thermal insulation in high-pressure and temperature experiments using a laser-heated diamond anvil cell (LH-DAC). We identified conditions for rapid deposition of an alumina layer on diamond anvils, showing deposition rates as high as 0.67 um/hr. We also investigated the deposition conditions of zirconia, which have lower thermal conductivity than alumina. Laser-heating tests were performed at high pressures and temperatures to evaluate the thermal insulation of the oxide film deposited on the diamond anvils. The heating efficiency of zirconia-deposited anvils was higher than that of the alumina-deposited ones. Our zirconia-sputtered anvils were capable of generating up to 2580 K at around megabar pressure without additional thermal insulation, demonstrating the potential of this technique for ultra-high temperature generation.

Realization of low specific-contact-resistance on N-polar GaN surfaces using heavily-Ge-doped n-type GaN films deposited by low-temperature reactive sputtering technique

We developed a low-temperature ohmic contact formation process for N-polar GaN surfaces. Specific-contact-resistances of 9.4 × 10−5 and 2.0 × 10−5 Ω cm2 were obtained using Ti/Al metal stacks on heavily-germanium-doped GaN films, which were deposited at 500 °C and 600 °C using a radical-assisted reactive sputtering method, respectively. The electrode sintering temperature was as low as 475 °C. Carrier concentrations for the 500 °C and 600 °C samples were 2.6 × 1020 and 1.8 × 1020 cm−3, respectively. These results suggest that this method is highly effective in reducing the contact resistance of GaN devices with low thermal budgets.

Exploring the Nb2O5 coating deposited on the Ti-6Al-4V alloy by a novel GE-XANES technique and nanoindentation load-depth

This research group has been demonstrating the significant advantages of using Nb2O5 coatings for functionalizing titanium, aluminium, and stainless steels. Regarding the biomedical sector and considering Ti-6Al-4V alloy, the reactive sputtering technique improved the cell viability, the osteogenic performance of cells involved in the osseointegration process as well as the ability to delay bacterial proliferation. The characteristics of the Nb2O5 coatings were assessed before by using standard methods, which provide information only a few tens of nanometers depth. Given that the Nb2O5 coating fabricated in this work exhibits a thickness of approximately 300 nm, the GE-XANES technique emerges as the most suitable method for this analysis. Additional information was provided with the aid of nanoindentation load-depth (P-h) curves. GE-XANES results indicated the formation of a homogeneous layer of Nb2O5 coating on the Ti-6Al-4V surfaces. The deposition process improved the surface hardness of the Ti-6Al-4V alloy (4.38 GPa versus 5.62 GPa) considering the 2 mN load.

Niobium and carbon nanostructured coatings for corrosion protection of the 316L stainless steel

This work aims to investigate the influence of niobium and carbon nanostructured coatings on the corrosion resistance of the 316L SS. The coated and uncoated specimens were morphologically and structurally characterized by using OM, SEM/EDX, DRX, FTIR, Raman spectroscopy and XPS techniques. The corrosion behaviour was assessed by OCP, PPc, EIS as well as immersion tests in 0.6 mol L−1 NaCl solution. In addition, the average contact angles were used to evaluate the surfaces free energy by the Van Oss interfacial tension component theory approach. Results showed that the surface treatments positively influenced the corrosion resistance of the 316L SS and the coatings act as a protective barrier against corrosion process. The reactive sputtering technique increased the wettability of the surfaces in relation to the base material. Considering applications in aggressive media, the 316L SS/Nb2O5 specimen exhibits superior performance when compared to the base material and 316L SS/carbon.

Benzene vapor sensing performance of different phases of copper oxide (CuxOy) thin films

Three different phases of copper oxide can be grown by thin-film deposition techniques, which differ in the oxidation state of copper. However, few studies have focused on comparing and considering sensing performance of these phases. The current study scrutinizes the benzene vapor sensing properties of various phases of copper oxide that can be used for the development of sensing device based on CuxOy thin films. RF reactive sputtering technique was employed, and different phases of copper oxide (CuO, Cu2O, and Cu4O3) were grown by tuning the sputtering power and reactive gas. The samples with phases of CuO, Cu2O, and CuO/Cu2O showed the response to benzene at different operating temperatures while the sample with the Cu4O3 phase was not sensitive to target vapor. The results demonstrated that the device based on CuO thin film can be a promising candidate to detect benzene vapor due to its remarkable sensitivity, selectivity, and stability.

Employment of Silicon Nitride Films Prepared by DC Reactive Sputtering Technique for Ion Release Applications

In this work, silicon nitride (Si3N4) thin films were deposited on metallic substrates (aluminium and titanium sheets) by the DC reactive sputtering technique using two different silicon targets (n-type and p-type Si wafers) as well as two Ar:N2 gas mixing ratios (50:50 and 70:30). The electrical conductivity of the metallic (aluminium and titanium) substrates was measured before and after the deposition of silicon nitride thin films on both surfaces of the substrates. The results obtained from this work showed that the deposited films, in general, reduced the electrical conductivity of the substrates, and the thin films prepared from n-type silicon targets using a 50:50 mixing ratio and deposited on both surfaces of a titanium substrate reduced the electrical conductivity of this substrate by 30%. This reduction in the release of ions from the coated metal substrate is attributed to the dielectric properties of the deposited silicon nitride thin films. This result is very important and applicable. This work represents the first attempt in Iraq to study such effects and may represent a good starting point for advanced studies in biomedical engineering.

Structural and Hardness Characteristics of Silicon Nitride Thin Films Deposited on Metallic Substrates by DC Reactive Sputtering Technique

Structural and Hardness Characteristics of Silicon Nitride Thin Films Deposited on Metallic Substrates by DC Reactive Sputtering Technique

Growth of Zn1−xNixO Thin Films and Their Structural, Optical and Magneto-Optical Properties

The radio frequency (RF) reactive sputtering technique has been used to prepare Zn1−xNixO thin films with 0 ≤ x ≤ 0.08. Composite targets were obtained by mixing and pressing NiO and ZnO powders. Sapphire, quartz and glass were used as substrates. X-ray diffraction analysis of Ni-doped ZnO films indicates that all samples are crystalised in a hexagonal wurtzite structure with a preferred orientation along the (002) plane. Any secondary phase, corresponding to metallic nickel clusters or nickel oxides was not observed. High-resolution transmission electron microscopy (HR-TEM) image observed for Zn1−xNixO thin film shows a strong preferred orientation (texture) of crystalline columns in the direction perpendicular to the substrate surface. Different surface morphology was revealed in AFM images depending on the film composition and growth condition. Optical absorption spectra suggest the substitution of Zn2+ ions in the ZnO lattice by Ni2+ ions. The energy bandgap value was also found a complex dependence with an increase in Ni dopant concentration. In photoluminescence spectra, two main peaks were revealed, which are ascribed to near band gap emission and vacancy or defect states. Faraday rotation demonstrates its enhancement and growth of ferromagnetism with the increase in Ni content of Zn1−xNixO thin films at room temperature.

X-ray Photoelectron Spectroscopy (XPS) Analysis of Ultrafine Au Nanoparticles Supported over Reactively Sputtered TiO2 Films.

The impact of a titania (TiO2) support film surface on the catalytic activity of gold nanoparticles (Au NP) was investigated. Using the reactive dc-magnetron sputtering technique, TiO2 films with an amorphous, anatase, and nitrogen-doped anatase crystal structure were produced for a subsequent role as a support material for Au NP. Raman spectra of these TiO2 films revealed that both vacuum and NH3 annealing treatments promoted amorphous to anatase phase transformation through the presence of a peak in the 513–519 cm−1 spectral regime. Furthermore, annealing under NH3 flux had an associated blue shift and broadening of the Raman active mode at 1430 cm−1, characteristic of an increase in the oxygen vacancies (VO). For a 3 to 15 s sputter deposition time, the Au NP over TiO2 support films were in the 6.7–17.1 nm size range. From X-ray photoelectron spectroscope (XPS) analysis, the absence of any shift in the Au 4f core level peak implied that there was no change in the electronic properties of Au NP. On the other hand, spontaneous hydroxyl (–OH) group adsorption to anatase TiO2 support was instantly detected, the magnitude of which was found to be enhanced upon increasing the Au NP loading. Nitrogen-doped anatase TiO2 supporting Au NP with ~21.8 nm exhibited a greater extent of molecular oxygen adsorption. The adsorption of both –OH and O2 species is believed to take place at the perimeter sites of the Au NP interfacing with the TiO2 film. XPS analyses and discussions about the tentative roles of O2 and –OH adsorbent species toward Au/TiO2 systems corroborate very well with interpretations of density functional theory simulations.

Reactively sputtered CdS:O buffer layers for substrate Sb2Se3 solar cells

Antimony selenide (Sb2Se3) is an emerging and promising photovoltaic material. High controllability for the energy level of buffer layers is greatly desirable for achieving higher performance Sb2Se3 solar cells due to the formation of heterojunction at the buffer/Sb2Se3 absorber interface. In this work, the CdS:O buffers were prepared by using a reactive sputtering technique including an Ar/O2 mixture gas and a CdS ceramic target, and a composite buffer were fabricated with a structure of CBD-CdS (∼10 nm)/CdS:O. The interface damage induced by sputtering is investigated, and untra-thin CBD-CdS is performed to recover the plasma induced damage at the CdS:O/Sb2Se3 heterojunction interface. By optimizing the S/(S+O) composition ratio and the phase component of the composite buffer, wide band-gap buffer layers were achieved, and the device spectra response and device parameters JSC and VOC were improved. It was found that the composite CdS:O buffer optimizes the heterojunction interface band alignment and further efficiently reduce the interface recombination, enhanced the transfer and collection of photogenerated carriers.

Synthesis of nanostructure Ta2O5 coatings using plasma reactive sputtering technique for optical filter application

Titanium bentoxide Ta2O5 deposited on glass substrates by were heated to 400 °C for 1, 2 and 6 hours. The as-deposited Ta2O5 films deposited by DC reactive sputtering show amorphous structure, the structure improved to crystalline after increasing annealing temperature. When the annealing time rises to 6 hours, Ta2O5 films with β-phase structure was obtained. The basic and optical properties of arranged films have been considered utilizing XRD and UV-Visible spectroscopy. The XRD comes about appeared that all films are polycrystalline in nature with orthorhombic structure and favored introduction along (0140) plane. The crystallite size was calculated using Scherrer formula and it is found that the 2 hrs sputtering time, 3Kv, 10Amp and 4×10-2mbar. Maximum crystallite size was (27.5nm). The absorbance and transmittance spectra have been recorded in the wavelength extend of (300-1000) nm in arrange to think about the optical properties. The optical energy gap for permitted direct electronic move was calculated using Tauc condition with regard to vitality of photon. It is found that the band gap increases with increasing annealing times and its ranges between 3.2 eV and 3.75 eV for the prepared Ta2O5 thin films.

Growth Mechanisms of TaN Thin Films Produced by DC Magnetron Sputtering on 304 Steel Substrates and Their Influence on the Corrosion Resistance

In this work, thin films of TaN were synthesized on 304 steel substrates using the reactive DC sputtering technique from a tantalum target in a nitrogen/argon atmosphere. All synthesis parameters such as gas ratio, pressure, gas flow, and substrate distance, among others, were fixed except the applied power of the source for different deposited coatings. The effect of the target power on the formation of the resulting phases and the microstructural and morphological characteristics was studied using XRD and AFM techniques, respectively, in order to understand the growth mechanisms. Phase, line profile, texture, and residual stress analysis were carried out from the X-ray diffraction patterns obtained. Atomic force microscopy analysis allowed us to obtain values for surface grain size and roughness which were related to growth mechanisms in accordance with XRD results. Results obtained showed a strong correlation between the growth energy with the crystallinity of the samples and the formation of the possible phases since the increase in the growth power caused the samples to evolve from an amorphous structure to a cubic monocrystalline structure. For all produced samples, the δ-TaN phase was observed despite the low N2 content used in the process (since for low N2 content it was expected to be possible to obtain films with α-Ta or hexagonal ε-TaN crystalline structure). In order to determine the corrosion resistance of the coatings, electrochemical impedance spectroscopy and polarization resistance were employed in the Tafel region. The results obtained through this evaluation showed a direct relationship between the power used and the improvement of the properties against corrosion for specific grain size values.

Noise behavior of tungsten oxide doped amorphous vanadium oxide thin films

Noise properties of a-VWOx thin films deposited by reactive DC sputtering technique for microbolometer applications have been investigated. It was found from measurements that there is no random telegraph switching (RTS) noise of deposited films. Electrode material effects on the contact resistance were measured thereby using electrode structure consisted of two different metals. Various currents and electrode structures effects on 1/f noise measurements were studied. As a result of calculations, 1/f noise parameter was found as 3.2 × 10−13. This situation shows that developed a-VWOx is notably a suitable material for microbolometer applications.

Heterostructure Silicon Solar Cells with Enhanced Power Conversion Efficiency Based on Si x /Ni3+ Self-Doped NiO x Passivating Contact.

Developing efficient crystalline silicon/wide-band gap metal-oxide thin-film heterostructure junction-based crystalline silicon (c-Si) solar cells has been an attractive alternative to the silicon thin film-based counterparts. Herein, nickel oxide thin films are introduced as the hole-selective layer for c-Si solar cells and prepared using the reactive sputtering technique with the target of metallic nickel. An optimal Ni3+ self-doped NiOx film is obtained by tuning the reactive oxygen atmosphere to construct the optimized c-Si/NiOx heterostructure band alignment. A thin SiOx interlayer was further introduced to reduce the defect of the c-Si/NiOx interface with the UV–ozone (UVO) treatment. The constructed p-type c-Si/SiOx/NiOx/Ag solar cell exhibits an increase in the open voltage from 586 to 611 mV and achieves a 19.2% conversion efficiency.