Tungsten-doped ZnO transparent conducting films deposited by direct current magnetron sputtering

Highly conducting and transparent thin films of tungsten-doped ZnO (ZnO:W) were prepared on glass substrates by direct current (DC) magnetron sputtering at low temperature. The effect of film thickness on the structural, electrical and optical properties of ZnO:W films was investigated. All the deposited films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. The electrical resistivity first decreases with film thickness, and then increases with further increase in film thickness. The lowest resistivity achieved was 6.97 × 10⁻⁴ Ω cm for a thickness of 332 nm with a Hall mobility of 6.7 cm² V⁻¹ s⁻¹ and a carrier concentration of 1.35 × 10²¹ cm⁻³. However, the average transmittance of the films does not change much with an increase in film thickness, and all the deposited films show a high transmittance of approximately 90% in the visible range.     

Al-Mg-B thin films prepared by magnetron sputtering

Hard, nanocomposite aluminum magnesium boride thin films were prepared on Si (100) substrates with a three target magnetron sputtering system. The films were characterized by X-ray diffraction, atomic force microscope, electron micro-probe, Fourier transform infrared spectroscopy and nanoindentation. The results show that the maximum hardness of the as-deposited films is about 30.7 GPa and these films are all X-ray amorphous with smooth surfaces. The influences of substrate temperature and boron sputtering power on the quality of the films are discussed. From the results of this work, magnetron sputtering is a promising method to deposit Al-Mg-B thin films.     

非平衡磁控溅射类金刚石碳膜的性能

用非平衡磁控溅射的方法在室温下制备了光滑、均匀、致密的类金刚石(DLC)薄膜,分析和研究了DLC膜的形貌、结构和摩擦特性.结果表明,靶工作电流对DLC膜的沉积有重要的影响.随着工作电流的增大,薄膜的沉积速率增大,薄膜中sp3键的含量增加.薄膜的摩擦系数随着工作电流的增加略有增大,在摩擦的初始阶段,摩擦系数较高,随着摩擦循环次数的增加,摩擦系数逐渐减小,并逐渐趋于稳定.     

Preparation of strontium titanate thin films by mirror-confinement-type electron cyclotron resonance plasma sputtering

Using mirror-confinement-type electron cyclotron resonance (ECR) plasma sputtering method, strontium titanate (SrTiO₃) thin films have been prepared on Si and Pt/Ti/SiO₂/Si substrates at a low substrate temperature (below 450 K) in a low pressure (2.7×10⁻² Pa) environment of pure Ar and Ar/O₂ mixture. Prepared film surfaces were very smooth regardless of high deposition rate (8.5 nm/min). The composition ratio Sr/Ti of Sr to Ti in the films varied with the distance between the target and the substrate. All as-deposited films on Si substrates were found to be amorphous and were crystallized by post-deposition annealing using an electric furnace at 650 K, i.e. approximately 250 K lower than annealing for films obtained by conventional RF magnetron sputtering. Post-deposition annealing of these films using millimeter-wave radiation decreased the crystallization temperature to a value of 550 K. Furthermore, all as-deposited films on Pt/Ti/SiO₂/Si substrates by a plasma of Ar and O₂ gas mixture were found to be crystallized regardless of no substrate heating.     

微波ECR等离子体源增强非平衡磁控溅射DLC膜的制备与表征

介绍了微波ECR等离子体源增强非平衡磁控溅射设备的结构和工作原理,详细叙述了利用该设备制备类金刚石膜的过程。Raman光谱证实了薄膜的类金刚石特性;采用原子力显微镜(AFM)观察薄膜的微观表面形貌,均方根粗糙度大约为1．9nm,结果表明薄膜表面非常光滑;利用CERT微摩擦计进行摩擦、磨损和划痕实验,薄膜的平均摩擦系数较小,大约为0．175;DLC膜和Si衬底磨损情况的扫描电镜图片相对比,可以看到DLC膜的磨痕小的多,说明薄膜有较好的耐磨性能;划痕测试结果表明制备薄膜临界载荷大约为40mN。     

Studies of diamond-like carbon films prepared by ion beam-assisted deposition

Ion beam-assisted deposition offers a novel and unique process to prepare diamond-like carbon (DLC) films at room temperature, with particularly good interface adhesion. This advantage was explored in this study to deposit highly wear-resistant coating on bearing 52100 steel. Both dual ion beam sputtering and ion beam deposition were employed. Various bombarding species and energy were investigated to optimize the process. Raman, X-ray photoelectron and Auger electron spectroscopy were used to characterize the bonding structure of DLC. Extensive experiments were carried out to examine the tribological behaviour of the DLC/52100 system. A metal intermediate layer can help tremendously in wear resistance. The results are optimistic and may lead to useful applications.     

反应磁控溅射法沉积的氟化类金刚石薄膜的结构分析

以高纯石墨作靶、Ar／CHF3作源气体采用射频反应磁控溅射法室温下制备了氟化类金刚石薄膜(F-DLC)。发现随着射频功率的增加,F-DLC薄膜拉曼光谱的D峰与G峰强度之比ID／IG加大,薄膜中芳香环式结构比例上升。红外吸收光谱则显示射频功率增加导致薄膜中的氟含量上升．氟原子与碳原子以及芳香环的耦合加强。控制射频功率可以有效调制薄膜中的氟含量以及芳香环结构的比例,F—DLC可能成为热稳定性较好的碳氟薄膜。     

Synthesis and characterization of Cu3N-WC nanocomposite films prepared by direct current magnetron sputtering

Cu₃N-WC films were synthesized on an arc ion plated TiN_x interlayer by direct current magnetron sputtering. The Cu₃N-WC films, composed of columnar WC crystals 3-5 nm in size and amorphous Cu₃N phases, were grown using the layer-plus-island mode. Deposition rate of Cu₃N-WC films declined from 11.7 to 7.5 nm/min when the WC target power increased from 200 to 400 W because the Cu target was poisoned by the diffusion of WC molecules. Nano-indentation testing results showed that the highest measure of hardness of Cu₃N-WC films was up to ∼ 41 GPa and the H³/E^?2 value of the Cu₃N-WC_47.4 was around 0.41 GPa, indicating the excellent plastic deformation resistance of the film. Incorporation of the soft lubricant Cu₃N phase and the uniform distribution of WC hard phases resulted in significant improvements in friction coefficient and wear resistance. As such, Cu₃N-WC films have a good potential in future wear applications.     

Structural analysis of amorphous Si films prepared by magnetron sputtering

A study is presented on the structural changes occurring in thin amorphous silicon (a-Si) during thermal treatments. The a-Si films were deposited on single-crystalline Si substrates held at room temperature by magnetron sputtering of a Si target in pure Ar atmosphere, and therefore the films were hydrogen-free. All samples were annealed in vacuum and subsequently studied by electron paramagnetic resonance (EPR) and grazing incidence X-ray diffraction (GIXRD). A slight increase in the dangling bonds content at lower annealing temperatures, and then a strong increase of it at around 650 °C, suggested significant structural changes. The samples were also studied by grazing incidence small-angle X-ray scattering (GISAXS) which confirmed changes at the nanometric scale attributed to voids in the material. A nice correlation of the results of the three techniques shows advantages of this approach in the analysis of structural changes in a-Si material.     

Infrared transmission properties of germanium carbon thin films deposited by reactive RF magnetron sputtering

Germanium carbon (GeC) thin films were prepared on ZnS substrates by reactive RF magnetron sputtering in Ar and CH₄ mixtures with a Ge disc as the target. H content in the films was studied as a function of the deposition parameters and low H content GeC film was obtained. RF power had a little effect on IR absorptions, hence had a little effect on H content. IR absorption of the GeC film increased a little with the increase in partial pressure of CH₄ as well as total pressure of gas mixture. Increase in substrate temperature decomposed CH₄ and CH_x in the GeC film into C and H and H was desorbed from the film, lowering the IR absorption. However, high substrate temperature prevented CH₄ or CH_x from adsorbing onto the substrate, which decreased C content in the GeC film and increased the film's refractive index. Higher annealing temperature of the GeC film reduced H content, but high annealing temperature (500 °C) caused the graphitization of the GeC film and destroyed its continuity.     

Influence of Ni content on the structure and properties of Cr-Ni-N coatings prepared by direct current magnetron sputtering

Cr-Ni-N coatings were deposited on 304 stainless steel substrates using a conventional direct current magnetron reactive sputtering system in nitrogen-argon reactive gas mixtures. The influence of Ni content (0 ≦ x ≦ 20 at.%) on the coating composition, microstructure, and tribological properties was investigated by glow discharge optical spectroscopy, X-ray diffraction and transmission electron microscopy, scanning electron microscopy (SEM), nano-indentation, and pin-on-disk tests. The results showed that microstructure and properties of coatings changed due to the introduction of Ni. The ternary Cr-Ni-N coatings exhibited solid solution structures in spite of the different compositions. The addition of Ni strongly favoured preferred orientation growth of <200>. This preferred orientation resulted from the formed nano-columns being composed of grains with the same crystallographic orientation, as confirmed by SEM cross-sectional observations. The mechanical properties including the nano-hardness and reduced Young's modulus decreased with increasing Ni content. Pin-on-disk tests showed that low Ni content coatings presented higher abrasion resistance than high Ni content coatings.     

Effects of precursor evaporation temperature on the properties of the yttrium oxide thin films deposited by microwave electron cyclotron resonance plasma assisted metal organic chemical vapor deposition

Yttrium oxide thin films are deposited using indigenously developed metal organic precursor (2,2,6,6-tetra methyl-3,5-hepitane dionate) yttrium, commonly known as Y(thd)₃ (synthesized by ultrasound method). Microwave electron cyclotron resonance plasma assisted metal organic chemical vapor deposition process was used for these depositions. Depositions were carried out at a substrate temperature of 350 °C with argon to oxygen gas flow rates fixed to 1 sccm and 10 sccm respectively throughout the experiments. The precursor evaporation temperature (precursor temperature) was varied over a range of 170-275 °C keeping all other parameters constant. The deposited coatings are characterized by X-ray photoelectron spectroscopy, glancing angle X-ray diffraction and infrared spectroscopy. Thickness and refractive index of the coatings are measured by the spectroscopic ellipsometry. Hardness and elastic modulus of the films are measured by load depth sensing nanoindentation technique.C-Y₂O₃ phase is deposited at lower precursor temperature (170 °C). At higher temperature (220 °C) cubic yttrium oxide is deposited with yttrium hydroxide carbonate as a minor phase. When the temperature of the precursor increased (275 °C) further, hexagonal Y₂O₃ with some multiphase structure including body centered cubic yttria and yttrium silicate is observed in the deposited film. The properties of the films drastically change with these structural transitions. These changes in the film properties are correlated here with the precursor evaporation characteristics obtained at low pressures.     

The effect of sputtering power on the structure and photocatalytic activity of TiO2 films prepared by magnetron sputtering

TiO₂ films were fabricated by direct current reactive magnetron sputtering. The effect of the sputtering power on the film structures, morphologies, and properties was investigated in detail. It is found that the concentration of oxygen impurities increased with increasing sputtering power accompanied by the bandgap (E_g) narrowing and broadening of photoluminescence (PL) peaks. The oxygen impurities were found to mainly play the role of recombination centers, leading to the decrease of photocatalytic activity. Furthermore, the photoconductivity to dark conductivity ratio could be used to evaluate and even predict photocatalytic activity to some extent.     

电子束蒸发与磁控溅射镀铝的性能分析研究

通过对半导体器件电极制备的两种方法即电子束蒸发与磁控溅射镀铝的比较，详细分析了两种方法的膜厚控制、附着力，致密性、电导率和折射率等重要性能指标，测试结果分析表明磁控溅射铝膜的综合性能优于电子束蒸发。     

Characterization of copper oxide nanolayers deposited by direct current magnetron sputtering

Direct current reactive magnetron sputtering was used to deposit the thin layers of copper oxide (Cu₂O) on glass substrates. A solid disc of pure copper as the target was sputtered in an argon gas under sputtering pressures varying from 0.133 to 4 Pa. The effects of the sputtering power and pressure on the structural and optical properties of Cu₂O thin films were systematically studied. The deposited layers were characterized using X-ray diffraction, atomic force microscopy, profilometry and spectrophotometry. The optical transmission of the films was measured in the visible region. The increase in pressure resulted in a higher growth rate than increasing sputtering power. The increase in power produced Cu₂O thin films that were detrimental to the optical transmission of the films.     

Characterization of boron-doped diamond-like carbon prepared by radio frequency sputtering

Instead of the sophisticated deposition processes and boron sources reported in literature, the study used the radio frequency magnetron sputtering method to prepare boron-doped diamond-like carbon (DLC) films with p-type conduction. The adopted sputtering targets were composed of boron pellets buried in a graphite disc. The undoped DLC films prepared exhibited n-type conduction, based on the Hall-effect measurement. For boron content ≥ 2.51 at.%, the films showed semiconductor behavior converted from n-type to p-type conduction after annealing at 450 °C. B-DLC films with a boron content of 5.91 at.% showed a maximum carrier concentration of 1.2 × 10¹⁹ cm⁻³, a mobility of 0.4 cm²/V s, and an electrical resistivity of 1.8 Ω cm. The results of XPS and Raman spectra indicated that the motion of boron atoms was thermally activated during post-annealing, helping promote the formation of C-B bonds in the films. Moreover, the doping of boron in DLC films decreased sp³ bonding and facilitated carbon atoms to form sp² bonding and graphitization.     

Preparation of diamond-like carbon films by cathodic micro-arc discharge in aqueous solutions

Diamond-like carbon films (DLC) and silicon doped diamond-like carbon films were deposited on Ni substrate by cathodic micro-arc discharge at room temperature in aqueous solutions. The deposit potential was 130 V. The structure of the films was characterized by a scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman spectra and XPS analysis demonstrated that the films were diamond-like carbon clearly. SEM observation showed that the DLC films were uniform and the thickness was about 200 nm. Potentiodynamic polarization curve indicated the corrosion resistance of the Ni substrate was markedly improved by DLC films.     

Synthesis of high-density MgO films by a novel magnetron sputtering system

A novel magnetron sputtering system, which included simply designed two grids between target and substrate, was developed in our laboratory for the synthesis of high-density MgO films. In order to investigate the effect of grids assisted magnetron sputtering, MgO films were deposited by conventional magnetron, one grid assisted magnetron and two grids assisted magnetron. The saturated ion current density and Mg ion fraction in MgO discharges generated by grids assisted magnetron were increased in comparison with those obtained in conventional magnetron, which means that grids assisted magnetron led to the enhancement of plasma density. As a result of microstructure analysis, grids assisted magnetron produced a higher density MgO film with smoother surface compared to that obtained in conventional magnetron.     

Structures and magnetic properties of Co and CoFe films prepared by magnetron sputtering

Structures and magnetic properties of Co and CoFe films on Si(100) have been investigated by employing scanning tunneling microscopy, atomic force microscopy, and magneto-optic Kerr effect techniques. As the film thickness increases, Co or CoFe clusters with different sizes are observed. As the film thickness increases below 20 nm, the size of the metal clusters decreases. For thicker films, the surface roughness increases monotonously by increasing the thickness. The easy axis of magnetization for both Co/Si(100) and CoFe/Si(100) prefers to be in the surface plane. By deposition of the Co or CoFe overlayers, the evolution of the longitudinal coercive force shows similar trend to the surface roughness. Minimum coercive force coincides with the smallest roughness of the film. For a film with greater roughness, the observation of larger coercive force could be explained by the impediment of the propagation of domain wall motion by defects of the films. At a higher deposition rate, Co islands in triangle shapes with an edge length around 100 nm are observed. This nanostructure shows an hcp-Co with the c axis parallel to the surface plane and is observed to be able to stabilize the coercive force for Co/Si(100) films.     

The effects of plasma pre-treatment and post-treatment on diamond-like carbon films synthesized by RF plasma enhanced chemical vapor deposition

Diamond-like carbon (DLC) films were synthesized by RF plasma enhanced chemical vapor deposition and the effects of plasma pre-treatment and post-treatment on the DLC films were investigated. Experimental results show that the surface roughness of the substrate, ranging from 0.2 to 1.2 nm, created by the plasma pre-treatment, will affect the surface roughness of the DLC films deposited using methane as the carbon source. However, the film surface roughness (0.1-0.4 nm) is much smaller than that of the substrate. Raman analysis and hardness measurement by nanoindentation indicate that the structure and the hardness of the DLC films are relatively unchanged for the film surface roughness investigated. For the argon or hydrogen plasma post-treatment of the DLC films deposited using acetylene as the carbon source, it is found that surface roughness decreases with the post-treatment time. Although the hardness decreases after post-treatment, it remains relatively constant with increasing post-treatment time.