多弧离子镀沉积Ti/TiN多层薄膜的摩擦磨损及电化学性能

软硬交替多层结构的薄膜因其优异的抗摩擦磨损性能和耐腐蚀特性使其在工程领域具有重要的应用价值。利用多弧离子镀在不锈钢和Si(100)表面沉积了Ti N单层薄膜和3种不同Ti/Ti N调制比的多层膜,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、CSM摩擦磨损试验机和电化学工作站分别分析了薄膜的结构特征、耐磨损性能和电化学性能。结果表明:多层膜层状结构明显,Ti N相出现(111)面择优取向;Ti与Ti N沉积时间比为1∶5的样品具有较低的摩擦因数(0.26)和磨损率(6.6×10–7 mm3·N–1·m–1);在3.5%Na Cl溶液中,多层膜样品的腐蚀电流密度较不锈钢基体降低了两个数量级,腐蚀电位较不锈钢基体明显提高,表明多层膜可以提高不锈钢基体的耐腐蚀性。     

Characteristics of TiN thin films grown by ALD using TiCl4 and NH3

Titanium nitride thin film was deposited on a silicon wafer by the Atomic Layer Deposition (ALD) method using TiCl₄ and NH₃ as source chemicals. Nitrogen gas was used for carrying the TiCl₄ and purging the reactants. The gases were introduced into the reaction chamber in the sequence of TiCl₄?N₂?NH₃?N₂ for the saturated surface reaction on the wafer. TiN film was grown with [100] preferred orientation at 350°C, while with [111] preferred orientation at 450°C and higher temperatures. The deposition rate was constant as 0.17 Å/cycle irrespective of deposition temperature, which demonstrates TiN film was grown by the ALD growth mechanism. TiN thin films grown at a temperature higher than 450°C with thickness of 320 Å showed electrical resistivity as low as 72×10^?6 Ωcm.     

Microstructure and properties of CVD coated Ti(C,N)-based cermets with varying WC additions

In this paper, multilayer coatings of TiN/TiCN/Al₂O₃/TiN are deposited on the Ti(C, N)-based cermets containing WC, and the effect of WC on the growth and adhesion strength as well as the mechanical properties of the coating are investigated. The multilayer coatings deposited by chemical vapor deposition (CVD) are uniform and dense. TiN coating exhibits a dense fine-grained structures and the Ti (C,N) on TiN coating shows dense columnar structure. The α-Al₂O₃ layer deposited on transition coating presents coarse grains with limited voids. The grain size of the columnar crystals deposited on the substrates gradually decreases with WC addition. The Al₂O₃ layer shows a preferred growth orientation of (104) plane. For TiN/TiCN phase, a change in orientation from (111) to (200) is observed. Generally, the (200) preferred orientation enhances and (111) preferred orientation diminishes with increasing WC addition. Strong adhesion of the CVD coating is obtained due to a sufficient amount of chemical elements, especially tungsten, diffusing from the substrate to the interfacial layer. Scratch tests show that the adhesion strength of TiN/TiCN/Al₂O₃/TiN films gradually increases firstly, and then decreases. With the addition of WC, the hardness, elastic modulus and plasticity index increase at the beginning, and then decrease. The change in nanohardness and elastic modulus is related to the grain size, elemental diffusion, and preferred orientation of the coating.     

Optimization of GaMnAs growth in low temperature molecular beam epitaxy

We present a detailed growth optimization procedure and experimental results for the growth of GaMnAs magnetic semiconductors in low-temperature molecular beam epitaxy. They were explored by using in-situ monitoring of the surface reconstruction patterns, double crystal/high-resolution x-ray diffraction, conductivity measurement, and superconducting quantum interference device measurements. The results showed strong correlations among the measurements. The room temperature conductivity measurement, in particular, was found to be a useful tool in forecasting the ferromagnetic transition temperature of the films. High quality GaMnAs films could contain Mn up to ≈5% without MnAs segregation at substrate temperatures of 215–275°C. The highest transition temperature of 80 K, however, was measured from the sample with 3.7% Mn grown at the substrate temperature of 250°C and As₄ pressure of 1.4×10⁻⁶ torr for a growth rate of 0.25 μm/hr.     

Preparation of ZrO<Subscript>2</Subscript> dielectric layers by subsequent oxidation after Zr film deposition with negative substrate bias voltage

ZrO₂ dielectric layers were prepared by a two-step process, a deposition of pure Zr film with and without a negative substrate bias voltage and a subsequent oxidation of the Zr films. We focused on the effect of the negative substrate bias voltage on the Zr film deposition and the subsequent oxidation of the Zr films. As a result, the Zr film deposited at the substrate bias voltage of −50 V (Vs = −50 V) was found to have a high intensity peak of Zr (100) and a uniform and smooth surface. From the capacitance-voltage and current-voltage measurements of the ZrO₂ films, a high dielectric constant of 21 and the equivalent oxide thickness (EOT) of 2.6 nm were obtained on the oxidation layer of the Zr film deposited at Vs = −50 V. On the other hand, a low dielectric constant of 15 and the EOT of 3.6 nm was obtained on that of the Zr film deposited at Vs = 0 V. The leakage current density of the ZrO₂ film (Vs = −50 V) was 5.69×10⁻⁴ A/cm², and this value was much lower than the 1.21×10⁻⁴ A/cm² for the ZrO₂ film (Vs = 0 V). It was found that the two-step process by subsequent oxidation after film deposition using a negative substrate bias voltage is useful for obtaining high-quality dielectric layers.     

Characterization of titanium nitride films deposited by cathodic arc plasma technique on copper substrates

TiN films were deposited directly on Cu substrates by a cathodic arc plasma deposition technique. The films were then characterized by X-ray diffraction (XRD), grazing incidence X-ray diffraction (GID), (TEM), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The preferred orientation of the film changed from (200) to (111) with increasing film thickness. Analyses of both the XRD and GID results showed that in the highly (111) textured grains, the (111) plane was approximately parallel to the film surface, while in the (200) textured grains, the (200) plane was tilted away from the film surface. Small-elongated crystallites with a large aspect ratio and textured grains were found on the TiN surface. AES, which was employed to examine the concentration depth profile, showed no apparent interdiffusion between Cu and TiN during the growth of the film. XPS results showed that amorphous TiO₂, as well as titanium oxynitride, was present on the TiN surface. The spectra of Ti-2p, N-1s, O-1s and Cu-2p before and after the film being sputter etched through the entire film region were also discussed.     

Fabrication, microstructure and tribological behavior of pulsed laser deposited a-CNx/TiN multilayer films

a-CN_x/TiN multilayer films were deposited onto high-speed steel substrates by pulsed laser ablation of graphite and Ti target alternately in nitrogen gas. The composition, morphology and microstructure of the films were characterized by energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The tribological properties of the films in humid air were investigated using a ball-on-disk tribometer. The multilayer films consist of crystalline TiN, metallic Ti and amorphous CN_x (a-CN_x). With an increase in thickness ratio of CN_x to bilayer, the hardness of multilayer film decreases, friction coefficient decreases from 0.26 to 0.135, and wear rate increases. The film with thickness ratio of CN_x to bilayer of 0.47 exhibits a maximum hardness of 30 GPa and excellent wear rate of 2.5 × 10^− 7 mm³ N^− 1 m^− 1. The formation of tribo-layer was observed at contact area of Si₃N₄ ball. The film undergoes the combined wear mechanism of abrasion wear and adhesion wear.     

The effect of gallium concentration and substrate temperature on the properties of Ga-Doped ZnO thin films sputtered from powder compacted target

Gallium-doped zinc oxide films with an average thickness of 300 nm were grown on corning glass 1737 substrate by radio frequency (RF) magnetron sputtering using powder compacted target with Ga concentrations of 0 wt.%, 2 wt.%, and 4 wt.%. The structural, optical and electrical properties of the films were investigated. During sputtering, deposition temperature was varied from room temperature to 200°C in 50°C intervals. All films were polycrystalline, having a preferred growth orientation with thec-axis perpendicular to the substrate. By increasing Ga concentration and substrate temperature, the peak height corresponding to the (002) plane was significantly increased. Columnar structure was clearly observed in the film deposited with a Ga concentration of 4 wt.% regardless of deposition temperature. The lowest resistivity achieved was 4×10⁻³ Ωcm at a Ga concentration of 4 wt.% grown at 200°C. All doped films showed an overall transmittance in the visible spectra of above 90%.     

Effects of dopant content on optical and electrical properties of In<Subscript>2</Subscript>O<Subscript>3</Subscript>: W transparent conductive films

The In2O3:W (IWO) films with different W content were deposited on glass substrate using direct current sputtering method. The structure, surface morphology, and optical and electrical properties were investigated. Results showed that both the carrier concentration and carrier mobility were increased with the doping of W. The IWO film with the lowest resistivity of 1. 0× 10-3 Ω· cm, highest carrier mobility of 43. 7 cm2. W-1. s-1 and carrier concentration of 1. 4× 1020 cm-3 was obtained at the content of 2. 8 wt. ％. The average optical transmittance from 300 nm to 900 nm reached 87. 6％.     

Characteristics of IZSO films deposited by a co-sputtering system

In−Zn−Sn−O films were deposited on a polycarbonate (PC) substrate by a magnetron co-sputtering system using two cathodes (DC, RF) without substrate heating. Two types of ITO targets (target A: doped with 5 wt.% SnO₂, target B: doped with 10 wt.% SnO₂) were used as an In−Sn−O source. The ITO and ZnO targets were sputtered by DC and RF discharges, respectively, and the composition of the In−Zn−Sn−O films was controlled via the power ratio of each cathode. In the case of ITO target A, the lowest resistivity (4.3×10⁻⁴ Ωcm) was obtained for the film deposited at the RF power (ZnO) of 55W. In the case of ITO target B, the lowest resistivity (2.9×10⁻⁴ Ωcm) of the film was obtained at the RF power (ZnO) of 30W, which was attributed to the increase in carrier density. Hall mobility decreased with increasing carrier density, which could be explained by the increase in ionized impurity scattering.     

TiN, TiN gradient and Ti/TiN multi-layer protective coatings on Uranium

Single-layer TiN, gradient TiN and multi-layer Ti/TiN coating were deposited on silicon and uranium substrates by means of arc ion plating technique. The main phase in the single-layer TiN coating was TiN with a (111) preferred orientation. Ti and TiN were observed in the TiN gradient coating and Ti/TiN multi-layer coatings. The single-layer TiN coating has demonstrated the best wear resistance among the three coatings. Compared with the bare U substrate, the corrosion potential E_corr of the multi-layer Ti/TiN coatings is increased by 580 mV, and the corrosion current density I_corr is decreased at least by two orders of magnitude. The multi-layer Ti/TiN coatings possessed the highest corrosion resistance among the three coating in a 0.5 μg/g Cl⁻ solution.     

Microstructure and hardness of hollow cathode discharge ion-plated titanium nitride film

Titanium nitride (TiN) films were deposited on 304 stainless steel substrate by hollow cathode discharge (HCD) ion-plating technique. The preferred orientation and microstructure were studied by x-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Microhardness of the TiN film was measured and correlated to the microstructure and preferred orientation. The results of TEM study showed that the microstructure of TiN film contains grains with nanometer scale. As the film thickness increases, the grain size of TiN increases. The x-ray results show that TiN(111) is the major preferred orientation of the film. The hardness of TiN film is primarily contributed from TiN(111) preferred orientation.     

Fabrication and characterization of Bi-substituted yttrium iron garnet films by pulsed laser deposition

We have systematically investigated the effects of processing parameters, including various oxygen pressures (Po₂) ranging from 200 to 1000 m Torr and substrate temperatures (T_s) ranging from 500 to 750°C, on the characteristics of Bi-substituted yttrium iron garnet (Bi:YIG) films grown on (111) gadolinium gallium gamet (GGG) substrates. Bi: YIG films were grown using a pulsed laser deposition method with an ArF excimer laser (λ=193 nm). Although the compositions of all the Bi:YIG films grown at the constant T_s of 600°C were close to the target composition irrespective of Po₂, the Bi contents were slightly increased with increasing Po₂, which was consistent with the variation in Faraday rotation angles (θ_F). In addition, the crystallinity of the Bi:YIG films was deteriorated with increasing Po₂, and their grains became irregular. At T_s above 700°C, Bi-deficient yttrium iron garnet films were grown. Consequently, high quality epitaxial Bi:YIG films exhibiting Faraday rotation angles of −1.0≈−1.5 degree/μm were successfully grown at the substrate temperatures in the range of 500–650°C when the Po₂ of 200 mTorr was used.     

Effect of substrate bias voltage on the texture and microstructure of Cu thin films deposited by ion beam deposition

Cu thin films deposited by non-mass separated ion beam deposition under various substrate bias voltages were investigated. The film textures and microstructure were analyzed by X-ray diffraction and field emission scanning electron microscopy, and the resistivity of the film was measured with the Van der Pauw method. It was found that the optimum negative substrate bias voltage for Cu films was −50 V. The Cu films deposited without substrate bias voltage showed a columnar grain structure with small grains and random orientation. However, when a substrate bias voltage of −50 V was applied, the Cu films had a non-columnar structure with a strong (111) texture and large grains. The electrical resistivity of the Cu films decreased remarkably with increasing negative substrate bias voltage, and reaching a minimum value of 1.8±0.13 μΩ cm at the substrate bias voltage of −50V.     

脉冲偏压占空比对TiN/TiAlN多层薄膜微观结构和硬度的影响

目的研究脉冲偏压占空比对TiN/TiAlN多层薄膜微观结构和硬度的影响规律。方法利用脉冲偏压电弧离子镀的方法,改变脉冲偏压占空比,在M2高速钢表面制备5种TiN/TiAlN多层薄膜,对比研究了薄膜的微观结构、元素成分、相结构和硬度的变化规律。结果 TiN/TiAlN多层薄膜表面出现了电弧离子镀制备薄膜的典型生长形貌,随着脉冲偏压占空比的增加,薄膜表面的大颗粒数目明显减少。此外,脉冲偏压占空比的增加还引起多层薄膜中Al/Ti原子比的降低。结论 TiN/TiAlN多层薄膜主要以(111)晶面择优取向生长,此外还含有(311),(222)和(200)晶相结构。5种多层薄膜的纳米硬度均在33GPa以上,当脉冲偏压占空比为20%时,可实现超硬薄膜的制备。     

Comparative studies on corrosion and tribological performance of multilayer hard coatings grown on WC-Co hardmetals

Multilayer TiN/TiCN/TiCN/TiC/TiN and TiN/TiCN/TiCN/TiC/Al₂O₃ hard coatings with total thicknesses of 15.7 μm and 9.3 μm were deposited on WC-10Co substrates using a chemical vapor deposition system. Evaluation of surface, cross-section morphologies, chemical composition and phases of coatings were analyzed by field emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) analyses respectively. Corrosion properties were evaluated in 3.5 wt% NaCl medium using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Tribological properties of fabricated multilayer hard coatings were evaluated using pin-on-disk tests. Results show that active dissolution of the WC-10Co occurred while the coated samples showed more anodic slopes as well as lower corrosion current densities. The corrosion current densities of 3.3 × 10⁻⁷ A/cm² and 7.5 × 10⁻⁸ A/cm² were obtained for the TiN/TiCN/TiCN/TiC/TiN and TiN/TiCN/TiCN/TiC/Al₂O₃ coated specimens which are much lower than 4 × 10⁻⁶ A/cm² of substrate. EIS analysis confirmed the results of potentiodynamic polarization curves. Delamination of the TiN coating and formation of titanium oxide compounds on the surface of the TiN/TiCN/TiCN/TiC/TiN coating revealed that oxidative wear mechanism is dominant for this sample, while adhesive wear mechanism was dominant for the TiN/TiCN/TiCN/TiC/Al₂O₃ coated sample.     

Thickness effect on interdiffusion of Fe/Pt multilayers

The effect of thickness on interdiffusion in Fe/Pt multilayer thin films was studied using rapid thermal annealing. [Fe(1 nm)/Pt(1 nm)]₂₀ and [Fe(3 nm)/Pt(3 nm)]₁₀ multilayers were prepared via DC magnetron sputtering and subsequently annealed at temperatures of 523 K to 603 K in an argon atmosphere in an infrared lamp furnace for a very short time. X-ray diffraction yielded the interdiffusion coefficients from the slopes of the satellite peak versus annealing time. The temperature dependence of interdiffusion in the range of 523 K to 603 K can be described by D(t)=3.42×10⁻¹⁵ exp(−0.83 eV/k_BT) (m²/s) for [Fe(1 nm)/Pt(1 nm)]₂₀ and D(t) =7.85×10⁻¹⁶ exp(−0.62 eV/k_BT) (m²/s) for [Fe(3 nm)/Pt(3 nm)]₁₀. The activation energy Q=0.83 eV for [Fe(1 nm)/Pt(1 nm)]₂₀ is higher than that of Q=0.62 eV for [Fe(3 nm)/Pt(3 nm)]₁₀. This phenomenon suggests that the atoms in the thicker film can move more easily in the interface and the lattice, which results in lower activation energy and higher diffusivity.     

Preparation and properties of tungsten-doped indium oxide thin films

Tungsten-doped indium oxide (IWO) thin films were deposited on glass substrate by DC reactive magnetron sputtering. The effects of sputtering power and growth temperature on the structure, surface morphology, optical and electrical properties of IWO thin films were investigated. The thickness and surface morphology of the films are both closely dependent on the sputtering power and the substrate temperature. The transparency of the films decreases with the increase of the sputtering power but is not seriously influenced by substrate temperature. All the IWO thin film samples have high transmittance in near-infrared spectral range. With either the sputtering power or the growth temperature increases, the resistivity of the film decreases at the beginning and increases after the optimum parameters. The as-deposited IWO films with minimum resistivity of 6. 4× 10-4 Ω·cm were obtained at a growth temperature of 225 ℃ and sputtering power of 40 W, with carrier mobility of 33. 0 cm2· V-1·s-1 and carrier concentration of 2. 8× 1020 cm-3 and the average transmittance of about 81％ in near-infrared region and about 87％ in visible region.     

Deposition and properties of highly <Emphasis Type="Italic">c</Emphasis>-oriented of InN films on sapphire substrates with ECR-plasma-enhanced MOCVD

InN films with highly c-axis preferred orientation were deposited on sapphire substrate by low-temperature electron cyclotron resonance plasma-enhanced metal organic chemical vapor deposition (ECR-PEMOCVD). Trimethyl indium (TMIn) and N2 were applied as precursors of In and N, respectively. The quality of as-grown InN films were systematically investigated as a function of TMIn fluxes by means of reflection high-energy electron diffraction (RHEED), X-ray diffraction analysis (XRD), and atomic force microscopy (AFM). The results show that the dense and uniform InN films with highly c-axis preferred orientation are successfully achieved on sapphire substrates under optimized TMIn flux of 0. 8 ml·min-1. The InN films reported here will provide various opportunities for the development of high efficiency and high-performance semiconductor devices based on InN material.     

TEM and DFT investigation of CVD TiN/κ-Al2O3 multilayer coatings

This paper investigates the interfacial structure in hot-wall CVD TiN/κ-Al₂O₃ multilayer coatings using both HREM and DFT modeling. Two multilayers with different thicknesses of the TiN layers (50 and 600 nm) separating the κ-Al₂O₃ layers are analyzed. The general microstructure of the two multilayers is relatively similar. The TiN layer in the thicker TiN/κ-Al₂O₃ coating is thick enough to be several TiN grains high. This means that epitaxial columns, which are often found in the thinner TiN/κ-Al₂O₃ coatings, are not present. However, the orientation relationships at the TiN/κ-Al₂O₃ interfaces are the same in both multilayers. The HREM investigations show that κ-Al₂O₃ (001) planes can grow directly on flat (111) TiN faces, without any other phases or detectable amounts of impurities, such as sulphur, present. Where the TiN layers are more curved, γ-Al₂O₃ can be grown, at least partly stabilized by the cube-on-cube orientation relationship between γ-Al₂O₃ and the underlying TiN. The DFT calculations show very similar adsorption strengths for an O monolayer positioned on Ti-terminated TiC(111) and TiN(111) surfaces, with preferred adsorption in the fcc site. O adsorption on N-terminated TiN(111) is much weaker, with preferred adsorption in the top site. Calculated elastic-energy contributions yield a higher stability for κ-Al₂O₃ on TiN(111) than on TiC(111) and a higher stability for κ-Al₂O₃ than for α-Al₂O₃ on both TiC and TiN. This indicates that the observed higher stability of κ-Al₂O₃ on TiC(111) than on TiN(111) is not due to the lattice mismatch, while the preferred epitaxial growth of κ-Al₂O₃ over α-Al₂O₃ can be partly attributed to the mismatch.