RF Magnetron Sputtering System Research Articles

Performance Improvement of a ZnGa2O4 Extended-Gate Field-Effect Transistor pH Sensor.

ZnGa2O4 sensing films were prepared using an RF magnetron sputtering system and connected to a commercial metal oxide semiconductor field-effect transistor (MOSFET) as the extended-gate field-effect transistor (EGFET) to detect pH values. Experimental parameters were adjusted by varying the oxygen flow rate in the process chamber to produce ZnGa2O4 sensing films with different oxygen ratios. These films were then treated in a furnace tube at an annealing temperature of 700 °C. The sensitivity and linearity of the constant current mode and the constant voltage mode were measured and analyzed in the pH range of 2-12. Under the deposition conditions with an oxygen ratio of 6%, the sensitivity reached 23.14 mV/pH and 33.49 μA/pH, with corresponding linearity values of 92.1 and 96.15%, respectively. Finally, the sensing performance of the ZnGa2O4 EGFET pH sensor with and without annealing processes was analyzed and compared.

Research on Flexible Transparent Conductive Electrodes Based on Ultra-Thin Ag in the Form of Grain Boundary with IZO Layer

In this paper, we investigated a transparent conductive electrode (TCE) that satisfies electrical, optical, and mechanical properties, formed by depositing ultra-thin Ag metal in the form of a random grain boundary with an indium zinc oxide (IZO) layer on a PET substrate. Commonly used ITO electrodes are brittle and difficult to apply to flexible devices. In contrast, IZO-based electrodes are mechanically flexible and can be used as flexible TCE, and have high electrical and optical properties. A 90 nm thick IZO electrode has a transmittance of 90.2% at a wavelength of 460 nm and a sheet resistance of 29.5 ohm/sq. In particular, Ag metal was deposited in the form of an atypical metal island using an RF magnetron sputtering system. At 3 nm there were few metal clusters in the form of islands, and many void channels were formed, resulting in high sheet resistance as well as a decrease in optical transmittance. However, about 5 nm thickness, the number of void channels decreased and the optical path changed, improving the electrical and optical properties. Results showed that the sheet resistance was reduced to 19.8 ohm/sq, and the transmittance was also increased to 91.1%. The mechanical properties were also found to be the same for conventional IZO and Ag/IZO TCE.

Defect engineering of RF sputtered Mg doped ZnO thin film for efficient photodetector application

Mg0.1Zn0.9O thin films were deposited using RF magnetron sputtering system on p-Si substrate, which were then annealed at various temperatures in air. The experiments showed that the crystallinity and surface roughness of the Mg0.1Zn0.9O films increased with the annealing temperature, meanwhile red shift was observed in the optical bandgap. The field emission scanning electron microscope (FESEM) analysis revealed that the surface morphology becomes more homogeneous with annealing temperature. A near band emission (NBE) and three deep level emission (DLE) (violet, blue and weak green emission) were observed from PL analysis for all the samples (as-deposited, 100 °C, 300 °C, 500 °C, and 700 °C). A red shift in the NBE (from 352 nm to 371 nm) and also disappearance of DLE at around 540 nm was observed with increase in annealing temperature. The MgZnO/p-Si device (500 °C) exhibits great photosensitivity (24-fold enhancement) as compare to as-deposited device because the thin film (TF) has high surface to volume ratio and the massive amount of photogenerated carriers. In addition, MgZnO/p-Si (500 °C) demonstrated quick device response with a rise time of 0.78 s and a fall time of 0.26 s under white light illumination.

Ultrasensitive nitric oxide gas sensors based on Ti-doped ZnO nanofilms prepared by RF magnetron sputtering system

It is aimed to explore the advantages of titanium doping and magnetron sputtering as opposed to chemical-based methods on the surficial and electrical characteristics of ZnO films and their gas sensing performance in particular. RF magnetron sputtering was employed to synthesize a pure ZnO nanofilm as a reference and Ti-doped ZnO nanofilms with various Ti contents. The doping process was done by sputtering Ti-doped ZnO targets developed through solid-state reaction, and doping content was determined by EDS analysis. All nanofilms exhibited pure hexagonal wurtzite structure and relatively flat and homogenous surfaces with a clear distribution of nanoparticles in the Ti-doped samples. The observed enhancement in the properties of the nanofilms was reflected in the ultimate performance of the gas sensor. In this regard, the sensor with 1 wt% Ti content showed the best gas sensing performance with an ultra-sensitivity of 1.72 for 1 ppm and 0.9 for 1 ppb NO gas at a relatively low working temperature of 167 °C. The sensor also acquired outstanding stability, quick responsivity, reproducibility and superior selectivity required for NO monitoring.

Mg doping effects on the microstructure and piezoelectric characteristics of ZnO:Li films deposited at room temperature using an RF sputtering deposition method

In this work, Density functional theory (DFT + U) was used to simulate Mg doped LZO (ZnO:Li 3 mol%) based on an atomic substitution concept. The calculation results indicate the piezoelectric constants e33, e31 and lattice constant a have a tendency to increase significantly due to Mg doping effects. Also, an RF magnetron sputtering system was used to prepare Mg-doped LZO films (ZnO: Li 3 mol%) with Mg doping concentrations of 0, 3, 6, 9 mol% at room temperature. A further analysis shows that when the proposed films are deposited at room temperature, Li atoms will bond with oxygen atoms to form Li2O2 to help to enhance the piezoelectric properties of the films. This is also found to be one of the reasons for the error in the simulated lattice constants.In addition, the doping of Mg induces lateral tensile stress in the ZnO structure. This phenomenon can produce lattice distortion and change the asymmetry of the ZnO atomic center at room temperature, thus improving the piezoelectric properties (piezoelectric coefficient d33 is increased from 4.5 to 26.3 pm/V). The reported d33 value is the highest compared to other reports on ZnO-based films deposited at room temperature.

Tribo-mechanical performance and antibacterial activity in (Cu, Zr)-alloyed Ti(Al)N coatings synthesized by reactive magnetron sputtering

In this work, copper and zirconium were added into the Ti(Al)N matrix to form deposited on TiAl(Cu, Zr)N coating using RF magnetron sputtering system in order to improve the mechanical, wear performance, and antibacterial activity. Results revealed that the TiAl(Cu, Zr)N coatings have a dense structure with (111) preferential orientation. The deposited TiAl(Cu, Zr)N coatings exhibited fcc-TiN structure, whereas the addition of Zr and Cu into the Ti(Al)N induced the appearance of Cu and ZrN. The solid solution strengthening and the increase in compressive residual stress (− 2.54 GPa) of Ti(Al, Zr)N coating with higher lattice strain (+ 0.1520) by the addition of Zr improved the hardness from 20.9 GPa. For the tribological property, the friction coefficient and wear rate decreased from (0.45, 5.9 × 10−3mm3/Nm) for the TiAlN to (0.29, 4.2 × 10−5mm3/Nm) for the Ti(Al, Zr)N, respectively, with high elasto-plastic H/E, H3/E2 (0.076, 0.121 GPa) ratios due to the low surface roughness, high adhesion, and nanocomposite structure. The results indicated the addition of Zr improves the friction property of Ti(Al)N coating. Although with their lower hardness than Ti(Al)N coating, the Ti(Al, Cu)N coating with 9.2 at.% Cu exhibited an excellent wear resistance and good antibacterial activity, which demonstrates its potential as a candidate material for biomedical application.Graphical

Defect regulation of AlN films based on Al-rich AlN targets

Aluminum nitride (AlN) films with low defect concentration were fabricated on Si substrates via RF magnetron sputtering system based on Al-rich AlN (Al-AlN) targets. The effects of Al-rich content on structure, defects and photoelectric properties of AlN films were investigated by x-ray diffraction (XRD), high resolution transmission electron microscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), ultraviolet-visible spectra, current–voltage (I–V) and capacitance–voltage (C–V) characteristics. In particular, the defects of AlN films were investigated by XPS and low-temperature PL analyses, indicating that Al-rich AlN targets can help to reduce the defects of Al vacancy and O impurity of AlN films with an optimal Al-rich content of 1.5 wt. % (A1.5). Schottky contact behavior between AlN films and Ti/Al/Ni/Au multi-layer electrodes were revealed from I–V curves of all samples based on parallel electrodes, and AlN metal-semiconductor-metal (MSM) devices prepared by A1.5 films exhibited the lowest leakage current of 2.43 × 10−8 A at the bias of 5 V. C–V tests indicate the less defect density and lower carrier concentrations of vertical structure of A1.5 devices. This work offers a feasible approach to regulate the defects of AlN films for practical application.

Enhanced Deep Ultraviolet Photoresponse in Ga doped ZnMgO Thin Film.

High Mg content (60%) ZnMgO samples with and without Ga dope were grown by an RF magnetron sputtering system. The effect of Ga dope on the ZnMgO sample and the respective ultraviolet photodetectors (UVPD) device’s performance were carefully studied by various experimental methods. The investigations of the structure and optical properties of the ZnMgO sample established that the Ga doped sample has a better crystal quality and larger band gap (5.54 eV). The current-voltage characteristics indicate that both the photocurrent and dark current were enhanced after Ga dope. Under 12 V bias, the undoped UVPD show two spectral response peaks at 244 nm and 271 nm with a responsivity of 1.9 A/W and 0.38 A/W, respectively. While the Ga doped UVPD showed only one response peak at 241 nm and the deep UV responsibility up to 8.9 A/W;, as the bias increased from 12 V to 60 V, the responsiveness raised to 52 A/W, with a signal to noise ratio (241 nm/700 nm) as high as 105. Combining the results of XRD, PL spectrum and XPS, the enhanced ultraviolet photoresponse of the Ga dope device contributed to improving the crystal quality and “dopant-defect pairing effect” caused by Ga doping, which led to a considerable reduction in the number of ionized impurities in the scatting centers, and enhanced the carrier’s mobility. Our work demonstrates that even a high Mg content ZnMgO can exhibit enhanced UV performance after a Ga dope due to the dopant-defect pairing effect, which confirmed the advantage of the use of ZnMgO in the deep-UV region.

Histomorphometric and biomechanical evaluation of the osseointegration around micro- and nano-level boron-nitride coated titanium dental implants

IntroductionTitanium dental implants has been coated with different materials such as polymers and biomimetic agents, bone morphogenetic protein, calcium phosphate to enhance surface properties of the titanium implants for osseointegration. The aim of this study was to evaluate the bone tissue healing around Boron Nitride-coated (BN-coated) titanium implants histomorphometrically and biomechanically and also observe the effect of different coating thicknesses on osseointegration. Materials and methodsBN was coated on dental titanium implants with two different coating thicknesses by using RF magnetron sputtering system. Totally fifty-four implants were inserted into the tibias’ of 12 New Zealand rabbits bilaterally under general anesthesia. All animals were sacrificed after 4-weeks. Bone-implant contact (BIC) and new bone area/total area ratios (BATA) were calculated. Also, the removal torque (RT) test was performed. ResultsThe highest new bone area in the medullary cavity was around the nano-BN-coated surface with 15.70%. In micro-BN-coated surface and control group, this ratio was determined as 10.48% and 8.23%, respectively. The BIC ratios in upper-side of implants and cortical-associated BIC ratios in lower-side were found significantly higher in control and micro-BN-coated group than nano-BN-coated group (p < 0.05). Similar BIC values were observed between control and micro-BN-coated groups (p > 0.05). BATA values did not show statistically significant differences between all three groups (p > 0.05). The RT values measured in all groups were found comparable and no statistically significant differences were found (p > 0.05). ConclusionNo inflammatory reaction developed around any implant. Relatively more new bone formation around nano-BN-coated titanium implants indicates the promising osseoinductive effect of BN coating. BN-coated implants showed similar biomechanical and histomorphometrical outcomes to that of the conventional titanium implants through a 4-week evaluation period.

Deposition and evaluation of Ta2O5 piezoelectric thin film on Pt crystal film

Tantalum pentoxide (Ta2O5) thin films were deposited on Pt(100)/Si(100) and SrRuO3(SRO)/Pt(100)/Si(100) substrates using an RF magnetron sputtering system. From the evaluated orientation and piezoelectricity of the deposited thin films, it was clarified that the Ta2O5 thin films were crystallized to λ-Ta2O5 without piezoelectricity on the Pt/Si substrates and to β-Ta2O5 with piezoelectricity on the SRO/Pt/Si substrates. The electromechanical coupling factor k t 2 of the deposited film containing β-Ta2O5 was measured to be 0.36% from the response of a high-overtone bulk acoustic resonator, whereas that of the deposited film containing λ-Ta2O5 was measured to be 0.03%. Furthermore, the enhancement of the electromechanical coupling factor of surface acoustic waves (SAWs) by adding a high-density Pt intermediate layer was clarified from the resonance property simulated by the finite element method. This enhancement was due to the distributed particle displacement of the SAWs throughout the Ta2O5 thin film.

Morphology of hydroxyapatite and Sr coatings deposited using radio frequency-magnetron sputtering method on nanotube formed Ti-6Al-4V alloy

In this study, morphology of hydroxyapatite and Sr coatings deposited using radio frequency- magnetron sputtering method on nanotube formed Ti-6Al-4V alloy was researched. For this study, nanotube formation on the samples was performed using anodization and then the hydroxyapatite (HA) and Sr thin film was coated using a RF magnetron sputtering system. For characterization of nanotube surface, the surface was observed using various instruments.The diameter of the nanotube increased and the nanotube layer increased as the applied voltage increased. The anatase phases were well formed on the surface and significantly increased as the applied voltage increased. HA and Sr coating layer was formed thicker than that of the HA coating layer and nanotubes were covered with HA and Sr. The surface roughness of the alloy increased as the voltage increased in the order of non-coating, HA and Sr coating, and HA coating. The contact angle of the alloy surface decreased in non-coating and HA coating, whereas, contact angle of HA and Sr coating increased as the applied voltage increased.

In vitro biocompatibility evaluation of Ti1.5ZrTa0.5Nb0.5Hf0.5 refractory high-entropy alloy film for orthopedic implants: Microstructural, mechanical properties and corrosion behavior

In the present research, a non-equimolar Ti1.5ZrTa0.5Nb0.5Hf0.5 RHEA film with a thickness of 1.025 µm was deposited on 316L, CoCrMo, and Ti6Al4V substrates by RF magnetron sputtering system. The microstructural characterizations showed that an amorphous and compact film with a continuous and cauliflower-like morphology was developed on the substrates. The hardness and elastic modulus of the deposited film, together with its adhesion, were determined by the nanoindentation. The RHEA-coated specimens exhibited much improved surface mechanical properties as compared with uncoated ones. The results of the scratch test demonstrated that the RHEA film provides high adhesion strength on the Ti6Al4V substrate compared to 316L and CoCrMo. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were carried out in phosphate buffer saline (BPS) solution at 37 ± 1 °C. In contrast to RHEA-coated 316L and CoCrMo specimens, RHEA-Ti6Al4V showed remarkable polarization resistance without any trace of pitting on its surface. According to the EIS measurement, the charge transfer resistance of the RHEA-Ti6Al4V specimen is significantly high, about 1.5 × 107 Ω cm2, owing to the strong bonding between the RHEA film and Ti6Al4V substrate.

Thermal Analysis of Energy Storage Capacity According to Thickness of Nickel/Chromium Alloy Layer

This paper examines a microconstruction consisting of nickel (Ni)/chromium (Cr) alloy thin-film. The total length of the microconstruction was 28 mm, the width was 0.2 mm, and the height was designed to be 1 μm. A thin-film of Ni/Cr alloy was co-sputtered on a silicon dioxide wafer patterned with photoresist via a RF magnetron sputtering system. The RF power ratios applied to the 4 inch target of Ni and Cr were 300 W:100 W (3:1), 300 W:150 W (2:1), and 150 W:150 W (1:1). The electrical resistance of the manufactured microconstruction was calculated and measured through Hall measurements. The temperature generated by applying 1–10 V to the microconstruction electrode was observed by using an infrared camera, and was summarized using a linear equation according to the power applied to each sample.

Rhombohedral symmetry in GaAs1− x N x nanostructures

Nanocrystalline structures of GaAs1−x N x thin films were prepared on 7059 Corning glass substrates by means of an RF magnetron sputtering system using a GaAs target and N2 as ambient-gas, at several values of substrate temperature (T s). The range of T s was chosen from room temperature to 400 °C. The nitrogen concentration into the GaAsN layers is (1.0% ± 0.2%). The average energy band gap of the GaAsN nanostructures, calculated from their optical absorption spectra, is 2.9 ± 0.2 eV. The Raman scattering spectra exhibit vibrational modes associated to the rhombohedral phase due to the crystalline structural transformation from the zincblende (ZB)-GaAs caused by the introduction of N into the lattice. From x-ray diffraction (XRD) patterns the ZB structure was identified with two additional pairs of peaks which were associated to two types of cubic to rhombohedral crystalline phase changes of the material. One type has a low deformation to a moderately elongated unit cell, and the second type has a higher deformation to a more elongated unit cell. The rhombohedral symmetry of the crystalline lattice in the GaAsN nanostructures has been calculated from XRD data to confirm experimental evidences. The total average grain size was determined from the Scherrer formula: 3.3 ± 1.2 nm. The photoluminescence spectra are characterized by a very broad emission band which encompasses photon energies from near infrared to UV (775–310 nm, i.e. 1.6–4.0 eV).

The effects of different doses of electron radiation on the electrical characteristics of ZnO interfacial Zn/n-Si junction

In this work, we have investigated the electrical characteristics of Zn/ZnO/n-Si/Au-Sb Schottky diodes before and after different doses (25 and 50 Gray) of electron-irradiation at room temperature. Initially, the ohmic contact has been made on n-Si semiconductor with Au-Sb alloy. After this process the ZnO thin film was grown on n-Si semiconductor by using RF magnetron sputtering system, and then the contact area is determined by sputtered Zn metal to surface of ZnO in DC sputtering system at about 10-6 Torr. The characteristic parameters of the junction such as ideality factor and barrier height values are calculated from I to V measurements and the carrier concentration, Fermi energy, diffusion potential, and barrier height values are calculated from reverse bias C-2–V measurements at various frequencies and room temperature. The I–V and C–V measurements of these diodes performed at room temperature and in dark. Experimental results showed that the values of the ideality factor increased and barrier height from forward-bias I–V measurements decreased and diffusion potential and the values of the barrier height obtained from reverse-bias C–V measurements decreased after electron-irradiation. However, changes in the characteristic parameters of the ZnO interfacial layer diode in 25 Gray of electron-irradiation were found to be less than those of the 50 Gray of electron-irradiation.

Improvement of thermal stability of Ta-N film in Cu metallization by a Zr-Si interlayer

Ta-N (10 nm)/Zr (20 nm) film was grown on n-type (100) silicon wafer at various substrate temperatures in a rf magnetron sputtering system, followed by in situ deposition of Cu. The Cu/Ta-N/Zr/Si samples were subjected to thermal annealing up to 800 ℃ under the protection of pure nitrogen gas. In order to investigate the effect of insertion of a thin Zr layer under Ta-N film on Ta-N diffusion barrier performance in Cu metallization, Cu/Ta-N/Zr/Si contact system was characterized by X-ray diffraction (XRD), four-point probe (FPP) measurement, scanning electron microscopy (SEM), and Auger electron spectroscopy (AES) depth profile. The results reveal that the microstructure of Ta-N films deposited on Zr is amorphous at different substrate temperatures. The barrier breakdown temperature of Ta-N/Zr film is about 100°C higher than that of Ta-N. It can effectively prevent the diffusion of Cu after annealed at 800°C. The improvement of diffusion barrier performance may be due to the production of Zr-Si layer with low contact resistivity after annealed at 800°C.

Deposition Rate and Electrochromic Properties of Ni Oxide Thin Films Deposited By Sputtering Using Water Vapor As a Reactive Gas

Ni oxide is well known electrochromic (EC) materials. And nickel hydroxide (Ni (OH)2) and oxyhydroxide (NiOOH) are considered to be electrochemically more active than nickel oxide (NiO). Reactive sputtering is one of the most commonly used techniques for obtaining compound thin films, however, deposition rate of compound thin film is low. We have reported that the deposition rate of sputtered nickel oxide thin film increased remarkably by substrate cooling using a liquid nitrogen and injection of water vapor (H2O) onto the target surface in argon (Ar) atmosphere [1]. In this study, we studied the effect of the direction of water vapor injection and the substrate temperature on deposition rate, composition and EC characteristics of the Ni oxide thin films.Ni oxide thin films were prepared by an RF magnetron sputtering system at substrate temperatures (Ts) of -80 °C and -170 °C. Ar and H2O were used as sputtering gas, and the flow rates of Ar and H2O were kept constant at 2.5 cc/min. H2O was injected onto the substrate or target surface. RF power and sputtering gas pressure were constant at 50 W and 50 mTorr, respectively. Film thickness was measured using a stylus profiler, and deposition rate was calculated using the film thickness and sputtering time. Crystal structure and chemical bonding state of the films were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. Optical and electrical properties of the films were studied by UV-Vis spectroscopy and four probe method. EC properties of the films were evaluated using cyclic voltammetry (CV) and chronoamperometry (CA) in a 1 M KOH aqueous electrolyte.Figure 1 shows the deposition rate of Ni oxide thin films deposited at Ts=-80 °C and -170 °C with the H2O injection onto the substrate or target surface. At Ts=-80 °C, high deposition rates of 30-35 nm/min were obtained regardless of the direction of H2O injection. The deposition rates are much higher than that obtained by conventional reactive sputtering at room temperature (4nm/min) [1]. In contrast, the deposition rate varied from 21 nm/min for H2O injection to substrate 38 nm/min (the highest deposition rate) for H2O injection to target at Ts=-170 °C. Highly transparent films with a transmittance above 80% were obtained regardless of the direction of H2O injection at Ts=-80 °C, however, the transmittances of the films deposited at Ts=-170 °C were low. From the four probe method measurement, the thin film deposited at Ts=-170 °C with H2O injection to substrate was found to be a mixed film of metal Ni and Ni oxide with a resistivity of 3.3×10-4Ωcm. The films deposited at Ts=-80 °C with H2O injection to substrate or target and the film deposited at -170 °C with H2O injection to target were considered to be NiO or Ni(OH)2. CV and CA measurements showed that the film deposited at Ts=-80 °C with H2O injection to target had good cycle stability and large transmittance change of 58% at a wavelength of 600nm.In summary, the deposition rate, chemical composition, and EC properties of the Ni oxide films were found to be strongly dependent on the substrate temperature and the direction of H2O injection. The films deposited with H2O injection to target at Ts=-170 °C showed the highest deposition rate and that deposited at Ts=-80°C with H2O injection to target showed the largest transmittance change.REFERENCES[1] Y. Yokoiwa et al, Jpn. J. Appl. Phys. 58 (2019) 055504. Figure 1

Effects of ITO Electrode on Electrochromic Properties of WO3 Thin Films in Visible and Near-Infrared Region

Indium tin oxide (ITO) thin films have been incorporated into electrochromic (EC) devices as a transparent conductive film. It is highly desirable that EC devices applied to a smart window can control both visible and infrared light, because infrared light accounts for about half of the energy of sunlight. In this study, we fabricated WO3 thin film on ITO thin films with different sheet resistances and studied their EC properties in visible and near-infrared region.ITO thin films deposited on glass were used as substrates. Tungsten oxide (WO3) thin films were deposited using RF magnetron sputtering system. Crystal structure was characterized by X-ray diffraction. Optical properties of the prepared samples were measured using UV-VIS-NIR spectrophotometer. The electrical resistance of the ITO thin films was measured by a four probe method. EC properties of the WO3 thin film were measured by cyclic voltammetry (CV) and chronoamperometry (CA) in a 0.01 M H2SO4 aqueous electrolyte.The transmittance of the high sheet-resistance ITO thin film (177 Ω/sq) decreased at a short wavelength region below 455 nm. However, it showed high transmittance above 70% in the visible and near-infrared region (455-2050 nm). In contrast, the low sheet-resistance ITO thin films showed high transmittance above 70% in a wavelength region of 335-1350 nm and its transmittance decreased above 1350 nm. The differences of the transmittance in short and long wavelength regions are considered to be caused by the Burstein-Moss effect and Drude model, respectively. Fig. 1 shows the transmittance spectra of the WO3 thin film with a thickness of 200 nm deposited on the ITO/glass substrates measured in air. Lines (1) and (2) show the transmittance spectra of colored and bleached states of WO3 thin film deposited on high sheet-resistance ITO thin film, and lines (3) and (4) show those of colored and bleached states of WO3 thin film deposited on low sheet-resistance ITO thin film. The WO3 thin film deposited on the high sheet-resistance ITO thin film showed a larger transmittance change and higher transmittance in bleached state in the near-infrared region than those of the WO3 thin film deposited on the low sheet-resistance ITO thin film. From these results, it was found that the selection of appropriate ITO electrodes is very important to obtain good EC property of WO3 thin films in visible and near-infrared region. Figure 1

Analysis of the Properties of Tungsten Carbide Thin Films According to the Sputtering Radio Frequency Power

In this study, we investigated characteristics of tungsten carbide thin film according to carbon and tungsten ratio. Tungsten carbide thin film was co-sputtered on silicon substrate and glass substrates using an RF magnetron sputtering system. To analyze the characteristics according to the composition ratio of the tungsten carbide thin film, the RF powers of carbon/tungsten target were divided into 100 W/100 W, 125 W/75 W, 150 W/50 W, and 175 W/25 W, respectively. Hall measurement and 4 points probes were used to measure electrical properties of the tungsten carbide thin films. Raman and field emission scanning electron microscope (FE-SEM) analysis were performed.

Improving the hardness of high entropy nitride (Cr0.35Al0.25Nb0.12Si0.08V0.20)N coatings via tuning substrate temperature and bias for anti-wear applications

The high entropy nitride coatings (Cr0.35Al0.25Nb0.12Si0.08V0.20)N with high hardness of 35 GPa and a high H3/E2 of 0.52 were fabricated by RF magnetron sputtering system via tuning the processing parameters, such as substrate temperature and bias. The chemical composition, crystal structure, grain size, and residual stress were measured and analyzed to determine the mechanisms of hardness improvement. The crystal structure maintained B1 face-center cubic structure throughout all the conditions. The hardness was improved from 28 GPa to 35 GPa by sputtering at 300 °C with −150 V bias. Such hardness was achieved due to increased densification and compressive residual stress. Furthermore, the wear test of high hardness and high value of H3/E2 coatings were performed at both ambient temperature and 600 °C. The correlation among H3/E2, oxidation resistance, and wear rate was addressed and discussed.