Process monitoring during AlN deposition by reactive magnetron sputtering

The effect of pressure on the reactivity of sputtered Al during reactive magnetron deposition was monitored by optical emission spectroscopy (OES) and a Langmuir probe. The deposition experiments were carried out varying the total pressure from 0.1 Pa to 1.2 Pa in an Ar/N₂ 7:1 flow ratio gas mixture. The deposited layers were analyzed by scanning electron microscopy (SEM) + energy dispersive analysis (EDS), glancing angle X-ray diffractometry (GAXRD) and X-ray photoelectron spectroscopy (XPS). Analysis of the films formed was based on the process parameters via plasma characterization. A correlation was found between the OES results and the amount of Al deposited. Under the present conditions, the base pressure was found to have a significant effect on the nature of the products deposited.     

双靶磁控溅射沉积Cu-W薄膜组织结构特征及其演变(英文)

采用双靶磁控溅射沉积Cu-W合金薄膜,通过XRD、TEM和HRTEM等方法分析沉积薄膜组织结构及其演变规律。在沉积初期,Cu-W薄膜呈非晶态,随着沉积过程的进行,在溅射粒子的轰击下已沉积薄膜逐渐晶化并形成类调幅结构,从而在沉积完成的微米级Cu-W薄膜中呈现表层为非晶态、底层为晶态的层状结构。采用Vegard规则对类调幅结构的固溶度进行计算,Cu-13.7%W薄膜是由固溶度分别为11%W和37%W的Cu(W)固溶体及纯Cu相组成;Cu?14.3%W薄膜是由固溶度分别为15%W和38%W的Cu(W)固溶体及纯Cu相组成;Cu-18%W薄膜是由固溶度分别为19%W和36%W的Cu(W)固溶体及纯Cu相组成。     

Structural and photoelectrochemical properties of Ti1−xWxO2 thin films deposited by magnetron sputtering

W-doped titanium dioxide is a promising candidate material for applications ranging from UV–VIS light photocatalytic reactions to catalyst support in proton-exchange membrane fuel cells, depending on the doping content. The present study reports on the possibility to synthesize substitutional Ti_1?xW_xO₂ thin films with 0 ≤ x ≤ 1 by magnetron co-sputtering from Ti and W metallic targets. Two routes were investigated starting from 1) crystalline titanium tungsten alloys deposited in non-reactive (pure Ar) mode, and 2) amorphous titanium tungsten oxides deposited in reactive (Ar + O₂ atmosphere) mode. The structure and phase stability after air annealing at 550 °C has been investigated by X-ray Diffraction (XRD). X-ray Reflectivity (XRR) was used to determine the change in film mass density upon annealing. Films of the non-reactive mode series could not be successfully fully oxidized into Ti_1?xW_xO₂ form. For the reactive mode film series, ternary Ti_1?xW_xO₂ oxides were obtained after air annealing and the crystal structure was changed from anatase to rutile with increasing W content in the range 0–33 at.%. Films with higher W content (0.33< x ≤ 1) eventually crystallized in the WO₃ triclinic structure. Photo-electrodes were elaborated from the deposited thin films on FTO coated glass, and they all showed photo-response when tested in acid solution, under UV–VIS illumination. Among the doped materials, the Ti_0.92W_0.08O₂ thin film showed the highest photo-current.     

反应磁控溅射制备Ti-Si-N薄膜的摩擦磨损性能

用反应磁控溅射方法,在不锈钢表面沉积Ti-Si-N薄膜.用原子力显微镜观察薄膜的表面形貌,Ti-Si-N颗粒尺寸小于0.1 μm,用亚微压入仪测试薄膜硬度,当硅的摩尔分数为9.6%时,薄膜硬度出现最大值47 GPa.球-盘式摩擦磨损结果表明,Ti-Si-N薄膜的耐磨性能明显优于TiN薄膜,加入少量硅元素后,TiN薄膜的抗磨损性能有显著提高,但Ti-Si-N薄膜的室温摩擦系数较高(0.6～0.8),高温下摩擦系数也仅轻微降低(550℃,0.5～0.6).由于Ti-Si-N薄膜的摩擦系数可能与磨损中氧化物生成量的增加有关,常温下Ti-Si-N薄膜的摩擦系数随硅摩尔分数的增加而增大,而高温下Ti-Si-N薄膜的摩擦系数随硅含量上升而降低.     

Investigation of Niobium oxynitride thin films deposited by reactive magnetron sputtering

Niobium oxynitride films were deposited using reactive magnetron sputtering of a niobium target in an Ar/O₂/N₂ atmosphere with fixed nitrogen flux in direct current (DC) and pulsed modes. For the DC sputtering mode the deposition rate was found to be twice as high as for the pulsed mode at lower oxygen to nitrogen ratios (O/N). Morphology investigation by scanning electron microscopy and atomic force microscopy showed that the coatings are getting very smooth with increasing oxygen content (average roughness R_a < 0.4 nm at oxygen contents > 40 at.%). X-ray diffraction measurements revealed that the niobium oxynitride films are X-ray amorphous for oxygen contents > 40 at.%. The electrical conductivity of the coatings was studied by the 4 point-probe method and was found to decrease with increasing oxygen content. Optical properties of Nb-O-N films were analysed by spectroscopic ellipsometry and transmission spectroscopy. The refractive index of transparent and semi-transparent films was found to be in the range of 2.3 and 2.6 (at 633 nm). The experimental results will be discussed with respect to the O/N ratios (range 1.2 < O/N < ∞) or the oxygen content (range 33.7 at.% < O < 67.3 at.%) in the films as measured by Rutherford backscattering spectroscopy and particle induced X-ray emission.     

Yttria-stabilized zirconia thin films deposited by pulsed-laser deposition and magnetron sputtering

Yttria-stabilized zirconia (YSZ, ZrO₂:Y₂O₃) was deposited on (100) silicon by two physical vapor deposition techniques: pulsed laser deposition (PLD) and reactive magnetron sputtering (RMS). PLD thin films were grown on silicon substrates at 500 °C from the ablation of a 8YSZ ceramic target by a KrF excimer laser. RMS thin films were obtained by direct current magnetron sputtering of a Zr/Y metallic target in an oxygen/argon atmosphere. The deposition rate of the PLD technique using an UV excimer laser delivering pulses at a repetition rate of 40 Hz was found two orders of magnitude lower than the RMS method one. Both techniques led to the growth of crystalline films with a (111) preferential orientation. PLD films were dense and featureless whereas RMS ones exhibited well defined but compact columnar structure. Growth of a YSZ film of about 1 μm covering a rough and porous commercial anode support (NiO-YSZ cermet) was successfully carried out with both methods.     

First-principles study of Ti3AC2 (A = Si,Al) (0 0 1) surfaces

We have systematically studied the mechanical properties and surface properties of (1 × 1) Ti₃AC₂ (A = Si, Al) (0 0 1) using the density functional theory (DFT). The calculated cleavage energy for each possible cleavage site shows that Ti–Si and Ti–Al are the weakest layers, while the Ti–C layer is the strongest one. It reveals that the main difference between Ti₃SiC₂ and Ti₃AlC₂ is that the Ti–Si bond is stronger than the Ti–Al bond. This shows the different mechanical and surface properties between them. The surface rumpling and surface energy of Ti₃SiC₂ and Ti₃AlC₂ are calculated. The study shows that the cleavage energy affects both the surface rumpling and the surface energy. The higher the cleavage energy, the larger the surface energy and surface rumpling. Furthermore, the most stable surface structures are predicted for different experimental conditions. The predicted surface structures agree with the available experimental results.     

磁控溅射沉积参数对硼碳氮薄膜沉积速率的影响

利用直流磁控溅射技术制备了三元硼碳氮(B-C-N)薄膜,通过改变靶功率、基体偏压、沉积温度和励磁线圈电流,在相同沉积时间内得到不同厚度的薄膜.采用纳米压入仪分析了沉积参数改变对B-C-N薄膜沉积速率的影响规律.结果表明,在低靶功率和高励磁电流的条件下沉积的薄膜,随着靶功率和励磁电流的增加薄膜沉积速率呈线性增长;薄膜的沉积速率随基体偏压的增加呈抛物线状下降;薄膜的沉积速率受基体是否升温影响很大,而受基体所加温度大小影响较小.     

Preparation and electrical properties of highly (1 1 1) oriented antiferroelectric PLZST films by radio frequency magnetron sputtering

Highly (1 1 1) oriented lead lanthanum zirconate stannate titanate (PLZST) films were synthesized on Pt/Ti/SiO₂/Si substrates by radio frequency (RF) magnetron sputtering. The microstructure and electrical properties of the films were investigated as a function of post-annealing temperature. Smooth and crack-free films obtained by post-annealing at 700 °C for 30 min, and exhibit a dense columnar microstructure with a grain size of ∼0.85 μm. The sputtered PLZST films of nominal composition Pb_0.97La_0.02 (Zr_0.60Sn_0.30Ti_0.10)O₃ display a high saturation polarization of ∼70 μC cm⁻², a low antiferroelectric-to-ferroelectric switching field (<100 kV cm⁻¹), a reasonable dielectric constant and a low loss tangent. This combination of properties makes them attractive for microdevice applications.     

Structural and optical properties of epitaxial ZnO thin films on 4H–SiC (0 0 0 1) substrates prepared by pulsed laser deposition

Epitaxially grown ZnO thin films on 4H–SiC (0 0 0 1) substrates were prepared by using a pulsed laser deposition (PLD) technique at various substrate temperatures from room temperature to 600 °C. The crystallinity, in-plane relationship, surface morphology and optical properties of the ZnO films were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence (PL) measurements, respectively. XRD analysis showed that highly c-axis oriented ZnO films were grown epitaxially on 4H–SiC (0 0 0 1) with no lattice rotation at all substrate temperatures, unlike on other hexagonal-structured substrates, due to the very small lattice mismatch between ZnO and 4H–SiC of ～5.49%. Further characterization showed that the substrate temperature has a great influence on the properties of the ZnO films on 4H–SiC substrates. The crystalline quality of the films was improved, and surfaces became denser and smoother as the substrate temperature increased. The temperature-dependent PL measurements revealed the strong near-band-edge (NBE) ultraviolet (UV) emission and the weak deep-level (DL) blue-green band emission at a substrate temperature of 400 °C.     

Electrochromic switchable mirror foil with tantalum oxide thin film prepared by reactive DC magnetron sputtering in hydrogen-containing gas

We have developed an electrochromic switchable mirror foil with a structure of Mg₄Ni/Pd/Al/Ta₂O₅/H_XWO₃/indium tin oxide on a polyethylene terephthalate (PET) substrate. When a voltage is applied to the device, the protons in the WO₃ layer move to the Mg₄Ni layer, which is then hydrogenated to form MgH₂ and Mg₂NiH₄. The hydrides have higher transparency, and thus the device can be effectively switched to a transparent state. We have previously reported a process where the device was fabricated by using a sulfuric acid solution to introduce protons to the WO₃ layer. However, the solution-based process appeared to have low adaptability to commercial processes. In the present work, we focused on fabricating the device by only solid-state processing. Specifically, a hydrogen-containing solid electrolyte layer of Ta₂O₅ thin film was fabricated by reactive dc magnetron sputtering in a mixture gas of argon, oxygen and hydrogen. We optimized the fabrication conditions of the hydrogen-containing Ta₂O₅ thin film for the device. In comparison with the device fabricated by the solution-based process, the device fabricated by only the solid-state process was more durable, retaining its optical switching properties for 7 days at a temperature of 40 °C and relative humidity of 80%. This result was related to the prevention of degradation on the surface of the Mg₄Ni thin film.     

Effects of oxygen addition on physical properties of ZnO thin film grown by radio frequency reactive magnetron sputtering

We deposited a ZnO thin film on a microslide glass substrate at room temperature by employing the RF reactive magnetron sputtering process. Our results revealed that deposition rate decreases by increasing O₂/(Ar + O₂) ratio that was caused by two mechanisms. The first mechanism was the reduction of plasma density and, thus, argon ion density; caused by the addition of highly electronegative oxygen. While the second mechanism was target poisoning caused by the oxidation of the target. Additionally, at the O₂/(Ar + O₂) ratio of ∼0.3 and the help of XPS analysis the optimum stoichiometry of ZnO thin film (the highest binding energy and content fraction of O^I peak (O-Zn bond)) and the best polycrystallinity (the lowest FWHM with largest grain size) was found.     

BiFeO3 thin films of (1 1 1)-orientation deposited on SrRuO3 buffered Pt/TiO2/SiO2/Si(1 0 0) substrates

BiFeO₃ (BFO) thin films of varying degrees of (1 1 1) orientation were successfully grown on SrRuO₃-buffered Pt/TiO₂/SiO₂/Si(1 0 0) substrates by off-axis radio-frequency magnetron sputtering. They demonstrate much enhanced ferroelectric behavior, including a much enhanced remnant polarization (2P_r ～ 197.1 μC cm^?2 at 1 kHz) measured by positive-up negative-down (PUND), at an optimized deposition temperature of 590 °C. The effects of film deposition temperature on the degree of (1 1 1) orientation, film texture, ferroelectric behavior, leakage current and fatigue endurance of the BFO thin films were systematically investigated. While the degree of (1 1 1) orientation is optimized at 590 °C, the defect concentration in the film increases steadily with increasing deposition temperature, as demonstrated by the dependence of leakage behavior on the deposition temperature. The polarization behavior is shown to strongly depend on the degree of (1 1 1) orientation for the BFO thin film. Oxygen vacancies are shown to involve in the conduction and dielectric relaxation of the BFO thin films deposited at different temperatures, as demonstrated by their dielectric and conduction behavior as a function of both temperature (in the range 294–514 K) and frequency (in the range 10^?1–10⁶ Hz).     

Sensitivity to humidity of TiO2 thin films obtained by reactive magnetron sputtering

This study presents results on the humidity-sensing properties of titanium dioxide thin films measured by a quartz microbalance. A novel two-layer structure, consisting of a polymer sub-layer and a sensing titanium dioxide layer, was fabricated on a quartz resonator. The polymer sub-layer was synthesized by a plasma process from hexamethyldisiloxane to protect the resonator's surface during the deposition of the titanium dioxide film by magnetron sputtering. The TiO₂ films were characterized by X-ray diffraction and Auger Electron Spectroscopy. The film composition was determined to be close to that of stoichiometric TiO₂. The sensitivity to humidity varied from 5 Hz/%RH to 7 Hz/%RH for TiO₂ film thickness lying in the range of 18-70 nm. An increase of film thickness in this interval led to a slight decrease in sensitivity, which is explained by water sorption occurring principally at the surface of the titanium dioxide film and a change of the morphology to a higher surface smoothness for thicker films. It was found that 30-60 min of sorption time is necessary to completely eliminate hysteresis, which suggests that the process is reversible.These results are promising for the development of sensor devices for measuring the relative humidity of air.     

Surface discharge characteristics of MgO thin films prepared by RF reactive magnetron sputtering

This paper describes the surface glow-discharge effect of MgO thin films prepared by reactive radio-frequency planar magnetron sputtering on the dielectric layer of an alternating-current plasma display panel. By introducing an MgO coating on the dielectric the discharge voltage decreases sharply, although the thickness is only a few tens of Ångstroms. The lowest discharge voltage is obtained for the sample prepared at a 30% O₂ content in an O₂+Ar gas mixture and at a sputtering gas pressure of about 5 mTorr. Moreover, high transparency (95%) is also obtained under the same experimental conditions. The samples prepared show more sputter-resistant properties than samples prepared by the electron-beam method and no cracks are observed on the surface after post-deposition annealing.     

316L不锈钢直流磁控溅射制备铝膜的工艺研究

采用直流磁控溅射在316L不锈钢上制备了高质量的Al膜,并利用扫描电镜、X射线衍射仪分别对镀层的形貌和结构及应力进行了分析。结果表明,温度、溅射功率之间的合理配置才能制备致密性高、表面缺陷少的Al膜,较优工艺参数温度为170℃、溅射功率1400 W;温度比溅射功率更容易改善结晶度,当溅射功率高、基体温度低,薄膜趋向非晶态;制备的薄膜应力小,最大约为0.176 GPa,微结构对应力影响大。     

The mechanism of low temperature deposition of crystalline anatase by reactive DC magnetron sputtering

It has been reported that TiO₂ film deposition by direct current (DC) magnetron reactive sputtering can occur according to the mechanism proposed by the theory of charged clusters (TCC). In the current study, the TCC was used to explain the mechanism of low temperature TiO₂ crystalline thin film growth. Highly oriented anatase thin films were deposited on unheated substrates. The degree of crystallinity of the thin film was found to depend on the cluster size and its crystallinity as well as the charging efficiency in the reactor. Larger clusters tend to be crystalline. These produce amorphous (nanocrystalline) films. Smaller clusters tend to be amorphous and adopt the structure of clusters already deposited to produce an ordered crystalline film. Increasing the substrate-to-target distance increased the cluster size. In addition, the charge density decreased as the target to substrate distance was increased. Clusters of <2 and 3 nm in diameter were observed at a substrate-to-target distance of 50 and 250 mm, respectively, which correspondingly produced crystalline and amorphous films. The DC power level did not appear to have a large effect on the cluster size nor did it affect the degree of crystallinity of the resulting thin film. The main factors affecting whether or not a crystalline film is deposited are the cluster size and the charge density in the reactor.     

Molecular beam epitaxial growth of zinc-blende FeN(1 1 1) on wurtzite GaN(0 0 0 1)

We report a study of the growth of iron nitride on gallium nitride using molecular beam epitaxy with Fe e-beam evaporation and rf N-plasma growth. Thin iron nitride layers of thickness about 16 nm were grown and monitored in situ using reflection high energy electron diffraction. The samples following growth were analyzed ex situ using a variety of techniques including X-ray diffraction, Rutherford Backscattering, and atomic force microscopy. By monitoring the structure, morphology, and lattice constant evolution of the iron nitride film, the crystal phase and orientation with respect to the GaN substrate are deduced; and from RBS data, the stoichiometry is obtained. The growth is discussed in terms of a 2-D to 3-D growth mode transition, and a critical thickness is estimated.