Influence Of Substrate Bias Voltage Research Articles

Mechanical integrity of PVD TiAlN-coated PcBN: Influence of substrate bias voltage and microstructural assemblage

Polycrystalline cubic boron nitrides (PcBN) have been increasingly used together with PVD coatings, mainly for hard turning operations. Within this context, effectiveness of coated PcBN as cutting tool is usually addressed by evaluation of its machining performance. Meanwhile, studies aiming to assess and understand the correlation between microstructural features and mechanical behaviour of the coating-substrate system are rather limited. Aiming to overcome such lack of information, in this study the influence of substrate bias voltage (−35 V as compared to −60 V) and microstructural assemblage (as a function of cBN content and binder chemical nature) on the mechanical integrity of TiAlN-coated PcBN systems is investigated. In doing so, contact damage response and coating adhesion strength of different coated-PcBNs are evaluated by means of indentation testing using distinct loading conditions (static and sliding) and tip geometries (spherical and conical). Such testing program is complemented by detailed FESEM inspection of the involved failure micromechanisms, as well as microstructural and micromechanical characterization of the deposited films. Results indicate that resistance against crack nucleation and propagation of coated PcBN, induced by either spherical or conical indentation, is enhanced by using harder (high content of cBN particles) and tougher (metallic binder) substrates (H-PcBN). Regarding bias voltage, systems with coatings deposited using a higher value (−60 V as compared to −35 V) show improved adhesive strength, this being particularly true for combinations involving low cBN content and ceramic binder substrate (L-PcBN). Similar beneficial effect was found, but exclusively in coated L-PcBN systems, regarding resistance to radial cracking emergence and to material removal through cohesive-failure chipping induced in Rockwell C tests. Although these findings are linked to the higher compressive residual stresses exhibited by coatings deposited under −60 V bias voltage, the latter does not translate in significant changes in microstructural and intrinsic mechanical properties of the TiAlN coating itself.

Influence of Substrate Bias Voltage on the Electrical and Optical Properties of IWO Thin Films

Influence of Substrate Bias Voltage on the Electrical and Optical Properties of IWO Thin Films

Influence of substrate bias voltage on microstructure and mechanical characteristics of TiAlSiN coating deposited by High Power Impulse Magnetron Sputtering (HiPIMS)

Substrate bias voltage has a presumably predominant and significant influence on the microstructural morphology and mechanical properties of HiPIMS deposited coatings. In the present investigation, it has been investigated in depth for a quaternary coating, TiAlSiN coating, which was deposited on the cemented carbide (WC-10 wt% Co) substrates. In this HiPIMS process, a pair of TiAl60 and a pair of TiSi34 targets were used. Four different substrate biases were set, i.e., −60, −90, −120, and −150 V to explore the difference in the coating characteristics. In every case, the substrate bias was also applied in pulsed mode but with an offset of 40 μs to the cathode pulse. Both cathode current and bias current were observed to increase from 87 to 98 A and 19 to 23 A, respectively, with increase of substrate bias voltage. As the bias voltage increased, the surface morphology became finer, and the cross-section morphology turned to be highly denser. The minimum and maximum grain sizes were estimated to be 7.23 nm and 9.90 nm at a substrate bias of −60 V and −150 V, respectively. Variation of Ti content (at.%) was noticed in the range of 28.35 to 30.71 with the increase of bias voltage. The maximum hardness of the coating was recorded to be 42.95 GPa at the bias voltage of −150 V. The adhesion level has been classified under HF1 in all deposition cases, as investigated by Rockwell indentation method, whereas the scratch test results suggest that a load range between 154 and 161 N is required for the complete delamination of the coating. Spallation and edge-chipping were the primary failure mechanisms during the scratching of the TiAlSiN coating.

Study of the influence of substrate bias voltage on the texture of Nb coatings deposited on a Cu substrate

The phase composition and texture of Nb coatings deposited using an inverted magnetron at voltages on the Cu substrate from 0 to –300 V were investigated by an X-ray method. With an increase in the voltage on the substrate, the thickness of the coating decreases from 9–10 μm at voltages up to –100 V and decreases to 2 μm at –250 V. The texture of the coatings varies non-monotonically from (110) to (111), while at high voltages on the substrate in the range from –250 to –300 V, the Nb coating is characterized by a textureless state.

Influence of substrate bias voltage on structure and properties of DC magnetron sputtered Ni–Zr alloy thin films

Abstract

Influence of substrate bias voltage on structure, mechanical and corrosion properties of ZrO2 thin films deposited by Reactive Magnetron Sputter Deposition

Zirconium oxide (ZrO2) thin films were grown onto 316L stainless steel by radio frequency magnetron sputtering (RFMS), at different substrate D.C. bias voltages (from 0 to −100 V). The deposition was performed using a pure zirconium target in the presence of an Ar-O2 gas mixture. The characterization of the deposited films was performed using scanning Electron Microscope, atomic Force Microscopy, X-rays diffraction, Raman spectroscopy, nanoindentation and potentiodynamic polarization. The structures of all ZrO2 films are crystalline. The monoclinic phase is predominant in the grounded films (0 V). However, the application of bias voltage depicts a tetragonal phase. Nanoindentation results reveal promoted values of the hardness of the ZrO2 films. Corrosion behavior of the films was studied in Hank's solution using the potentiodynamic polarization method. The comparison between the uncoated samples and the coated ones showed a reduction in corrosion current density for coated samples. The minimum corrosion rate of the film deposited at −100 V was 0.04992 mpy, which is about 18 times less than that of the uncoated steel (0.88135 mpy). The optimum anti-corrosion performance and hardness were obtained for ZrO2 deposited at a bias voltage of −100 V.

Influence of Substrate Bias Voltage on Structure, Morphology and Mechanical Properties of AlCrN Coatings Synthesized Using Cathodic Arc Evaporation

Influence of Substrate Bias Voltage on Structure, Morphology and Mechanical Properties of AlCrN Coatings Synthesized Using Cathodic Arc Evaporation

The influence of substrate bias voltage on the electrochemical properties of ZrN thin films deposited by radio-frequency magnetron sputtering: Biomedical application

Abstract In order to study the influence of the substrate bias on the properties of ZrN thin films deposited by radio-frequency magnetron sputtering for biomedical application. Films of ZrN were grown onto 316L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure zirconium target in Ar - N2 gas mixture. The substrate bias voltage was varied from 0 to −100 V, which produces a variation in the structural and electrochemical properties of the obtained films. The deposited films were characterized by X-Rays Diffraction, Atomic Force Microscopy, scanning force microscopy and potentiodynamic polarization.

Influence of Substrate Bias Voltage on Corrosion and Wear Behavior of Physical Vapor Deposition CrN Coatings

The objective of the present paper is to study the influence of the substrate bias voltage on the microstructure, composition, deposition rate, tribological and corrosion properties of CrN coatings obtained by DC magnetron sputtering on 90CrMoV8 steel and Si (100) substrates. The substrate bias voltage varied from 0 to − 700 V. The deposited films were characterized by SEM, XRD and potentiodynamic polarization. The wear behavior and coefficient of friction were determined and investigated after rotative tribometer tests. The results indicated that the substrate bias voltage considerably affected the intrinsic properties of the CrN films. Indeed, it significantly influenced the grain size and the root-mean-squared roughness which varied from 20 to 29 nm, and from 9 to 19 nm, respectively, when polarization changed from 0 to − 700 V. All the CrN coatings have a dense columnar structure and are well crystallized according to the XRD analyses. Nevertheless, it has been shown that the peaks intensity decreased by increasing the substrate bias voltage. By applying a substrate bias voltage, it was obvious that the friction behavior was enhanced, and the wear volume was decreased. Finally, the CrN coating obtained under a substrate bias voltage of − 500 V presented the best corrosion resistance and wear resistance probably due to its dense microstructure.

Influence of substrate bias voltage on crystallographic structure, optical and electronic properties of Al/(Ta2O5)0.85(TiO2)0.15/p-Si MIS Schottky barrier diodes fabricated by dc magnetron sputtering

Thin films of (Ta2O5)0.85(TiO2)0.15 were prepared on p-Si and quartz substrates by reactive magnetron sputtering and the influence of substrate bias voltage (Vb) on their structural and electrical properties was studied. The crystal structure of the prepared films was elucidated by X-ray diffraction (XRD) studies. The structure of the as deposited films was found to be amorphous and the surface roughness of the films was found to be low. The crystallinity of the films was observed to be improved by increasing the substrate bias voltage. The XPS results revealed that the composition of the films were nearly stoichiometric with Vb at 0V and −150V. The optical properties of the films at various substrate bias voltages were also studied. The optical band gap of the films formed at various Vb values from 0 to −150V decreased from 4.49 to 4.39eV as revealed from the optical transmission spectra. The fabricated Al/(Ta2O5)0.85(TiO2)0.15/p-Si metal-insulator-semiconductor (MIS) Schottky diodes leakage currents at −1.5V decreased from 4.65 × 10−6A (unbiased) to 3.73 × 10−8A (Vb = −100V). On the other hand, the sample biased at Vb= −150 V exhibited an increase in leakage current (2.99 × 10−4A) when compared to all other prepared samples. Furthermore, the electrical parameters such as Schottky barrier height and ideality factor were calculated for the Al/(Ta2O5)0.85(TiO2)0.15/p-Si MIS Schottky structure and systematically investigated as a function of substrate bias voltage using current-voltage (I-V) and capacitance-voltage (C-V) characteristics.

A Threshold Voltage Model of Tri-Gate Junctionless Field-Effect Transistors Including Substrate Bias Effects

In this paper, the influence of substrate bias voltage and substrate-induced surface potential (SISP) on threshold voltage of tri-gate junctionless field-effect transistors (TG-JLFETs) has been investigated. For this purpose, a quasi-3-D threshold voltage model of TG-JLFETs is presented considering the effects of both back-bias voltage and a lightly doped substrate. To incorporate the effect of SISP on the threshold voltage, the boundary conditions at the silicon–buried oxide interface have been modified accounting for the potential difference between substrate surface and substrate bulk. Model results are compared with the simulation results obtained using 3-D visual TCAD device simulator from Cogenda.

High-rate deposition of silicon films in a magnetron discharge with liquid target

Silicon coatings have been deposited on substrates made of low-carbon and high- carbon steels and tungsten in a magnetron discharge with liquid target at substrate bias voltages ranging from +100 V to -600 V. The structure of obtained coatings was examined by a scanning electron microscopy. The strong influence of substrate bias voltage on the coating structure was observed. The corrosion resistance of coated steel samples was examined in concentrated sulphuric, hydrochloric and nitric acids and their solutions. The resistance of coated tungsten samples against high-temperature oxidation was examined by their exposure to O2 gas at a pressure of 0.2 Pa and a temperature of 1073 K. The coatings deposited under bias voltages of+100 V and -600 V had dense structures and showed the best protective properties among all deposited coatings.

Influence of substrate bias voltage on the properties of TiO2 deposited by radio-frequency magnetron sputtering on 304L for biomaterials applications

The aim of this paper is to investigate the effect of the substrate bias, varied from 0 to −100V, on the structure and properties of the TiO2 thin films for biomaterials applications.The TiO2 films were grown onto 304L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure titanium target in Ar-O2 gas mixture.The variation of substrate bias voltage from 0 to −100V produces variations of structure and mechanical properties of the films. The deposited films were characterized by X-rays diffraction, nanoindentation and potentiodynamic polarization. Also, the friction and wear properties of TiO2 films sliding against alumina ball in air were investigated.Experimental results showed that the thickness increases for non-biased substrate voltage to Vs=−100V from 820nm to 1936nm respectively. The roughness is in the range of 50nm and 14nm. XRD results show that all structures of the films are crystalline and changed with varying the bias voltage. The anatase phase is predominant in the low negative bias range (0–50V). The hardness significantly increased from 2.2 to 6.4GPa when the bias voltage was increased from 0 to 75V and then slightly decrease to 5.1GPa as further increased to 100V. At the same time, the results indicate that TiO2 films deposited at −100V exhibited better wear resistance compared to the other samples, i.e. the minimum wear rates and the lower coefficient of friction of 0.16. In order to simulate natural biological conditions, physiological serum (pH=6.3), thermostatically controlled at 37°C, was used as the electrolyte for the study of the electrochemical properties. Comparison between the corrosion resistance of the uncoated and coated samples showed a reduction in corrosion current density for coated samples compared to the uncoated one. The best corrosion current density of the film deposited at −75V was 5.9nA/cm2, which is about 11 times less than that of the uncoated steel 68.3nA/cm2). The optimum anti-corrosion performance and hardness was obtained for TiO2 deposited at a bias of−75V.

Correlation between Microstructure of Copper Oxide Thin Films and its Gas Sensing Performance at Room Temperature

Radio-frequency magnetron sputtering using a Cu target was used to deposit cuprous oxide and cupric oxide thin films on silicon wafer. The substrate bias voltage and the O2 flow ratio were varied during the deposition. The deposited thin films were characterized using scanning electron microscope. We found that the spherical and pyramid shapes structure of copper oxide thin films were deposited at critical O2 flow ratio between 7 and 14%. The influence of substrate bias voltage was small and negligible. The deposited thin films were used for sensing characterization using ethanol vapor. Experimental results reveal that the pyramid shape of copper oxide thin film contribute to high respond rate when exposed to ethanol vapor. The respond and recovery rates which were measured at room temperature were very fast. This work had successfully demonstrated the formation of optimized copper oxide thin films and their usage for gas sensing application.

Structural, Electrical and Optical Properties Of Molybdenum Doped Zinc Oxide Films Formed By Magnetron Sputtering

Thin films of molybdenum doped (2.7 at.%) zinc oxide (MZO) were deposited on glass substrates held at room temperature by RF magnetron sputtering of mosaic target of Mo-Zn at different substrate bias voltages. The influence of substrate bias voltage on the structural, electrical and optical properties was investigated. The MZO films deposited on unbiased substrate were of amorphous, while those formed at substrate bias voltage of -40 V and above were of nanocrystalline. The crystallite size of the films improved with the applied bias voltage. At higher substrate bias voltage of -120 V the ion bombardment induced the high defect density in the films hence decrease in the crystallinity. The films formed at substrate bias voltage of -80 V exhibited low electrical resistivity of 1.2x10 -2 Ωcm and optical transmittance of about 79 %. These films showed optical band gap of 3.29 eV and figure of merit of 19 Ω -1 cm -1 .

Influence of substrate bias voltage on the microstructure of nc-SiOx:H film**Project supported by the Key Basic Research Project of Hebei Province, China (Grant No. 12963930D), the Natural Science Foundation of Hebei Province, China (Grant No. F2013201250), and the Science and Technology Research Projects of the Educational Department of Hebei Province, China (Grant No. ZH2012030).

Amorphous silicon oxide containing nanocrystalline silicon grain (nc-SiOx:H) films are prepared by a plasma-enhanced chemical vapor deposition technique at different negative substrate bias voltages. The influence of the bias voltage applied to the substrate on the microstructure is investigated. The analysis of x-ray diffraction spectra evidences the in situ growth of nanocrystalline Si. The grain size can be well controlled by varying the substrate bias voltage, and the largest size is obtained at 60 V. Fourier transform infrared spectra studies on the microstructure evolutions of the nc-SiOx:H films suggest that the absorption peak intensities, which are related to the defect densities, can be well controlled. It can be attributed to the fact that the negative bias voltage provides a useful way to change the energies of the particles in the deposition process, which can provide sufficient driving force for the diffusion and movement for the species on the growing surface and effectively passivate the dangling bonds. Also the larger grain size and lower band gap, which will result in better photosensitivity, can also be obtained with a moderate substrate bias voltage of 60 V.

Bias-assisted magnetron sputtering of yttria-stabilised zirconia thin films

Cubic yttria-stabilized zirconia (YSZ) thin films were deposited by reactive magnetron sputtering on NiO-YSZ fuel cell anodes under different conditions. The influence of substrate bias voltage, temperature and porosity on texture and morphology of the deposited films were investigated. Comparing film morphology of YSZ grown on NiO-YSZ anodes, it was found that films deposited on a substrate with a large porosity were columnar and contained voids regardless of the deposition parameters. It was shown that only using of anode support with very high surface quality, substrate heating up to 500 °C and pulsed substrate bias (about -30 V MF) during film deposition is necessary for deposition of non-columnar thin films without voids and cracks that may be suitable for SOFC application.

DLC Coating by HiPIMS: The Influence of Substrate Bias Voltage

Carbon-related materials are prepared using various physical vapor deposition (PVD) methods. High-power impulse magnetron sputtering is a PVD method that uses glow plasma and this method is employed to prepare diamond-like carbon (DLC) films. The densities of the glow current and the consumed power for an effective area of plasma generation are 1.4 ${\rm A}/{\rm cm}^{2}$ and 1.2 ${\rm kW}/{\rm cm}^{2}$ , respectively. A pulsed bias is applied to the substrate (subsequently called substrate bias voltage). The pressures of the background gas and the substrate bias voltages influence the surface morphology and the roughness of the deposited films. It is discovered that a critical pressure of 0.3 Pa and a critical bias voltage of ${-}{\rm 100}~{\rm V}$ is needed to change the DLC film characterization. A drastic change in these characteristics is seen for pressures ${ ; a bumping surface and dumpling-like aggregations are produced. In addition, there is a bias-voltage dependency on these films, as smoother surfaces are seen in a bias-voltage range that is higher than ${-}{\rm 100}~{\rm V}$ . This phenomenon may be related to the DLC structure, which is evaluated by Raman parameters of the deposited films. It is found that the position and the full width at half maximum of the graphite peak show a minimum and a maximum, respectively, at a bias voltage of ${-}{\rm 100}~{\rm V}$ . The results of X-ray photoemission spectroscopy reveal that the ${\rm sp}^{3}$ bond ratio indicates a maximum at a pressure of 0.3 Pa and at a bias voltage of ${-}{\rm 100}~{\rm V}$ . Thus, it is clear that the gas pressure of 0.3 Pa and the bias voltage of ${-}{\rm 100}~{\rm V}$ are critical values that change the pressure and bias dependence of the film characteristics.

Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO3 thin films

In this investigation, tungsten oxide (WO3) thin films have been deposited on unheated glass substrates by RF magnetron sputtering of tungsten target at constant oxygen partial pressure of 6×10−2 Pa, sputtering power of 150 W and at different substrate bias voltages in the range from 0 to -150 V. The structural and optical properties of the films were investigated by using X-ray diffraction, Fourier transform infrared spectroscopy and UV-Vis-NIR spectrophotometers. The films formed up to substrate bias voltage of -50 V were found to be amorphous in nature, while those films formed at -100 V showed a weak (200) reflection indicates the presence of monoclinic phase of WO3 in amorphous matrix. The optical transmittance of the films was in the range 78 – 95 % in the wavelength range of 500 – 1200 nm. The absorption band edge was shifted towards higher wavelength side with increasing substrate bias voltage. The optical band gap of the films decrease from 2.81 to 2.69 eV with increase of substrate bias voltage from 0 to -150 V respectively. The refractive index of the films increased from 2.19 to 2.27 with increase of substrate bias voltage from 0 to -150 V respectively.

Structural, surface morphological and optical properties of nanocrystalline Cu2O films prepared by RF magnetron sputtering: substrate bias effect

Cuprous oxide films have been prepared on glass substrates by sputtering of metallic copper target in an oxygen partial pressure of 2 × 10−2 Pa under different substrate bias voltages in the 0 to −100 V range employing RF magnetron sputtering technique. The influence of substrate bias voltage on the structural, surface morphological, electrical and optical properties has been studied systematically. The crystallite size of the films increases with the increase of substrate bias voltage up to −60 V. The films formed at substrate bias voltage of −60 V show low electrical resistivity of 12 Ω cm, larger crystallite size of 35 nm and optical band gap of 2.40 eV.