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.     

Preparation and characterization of ZnO/Cu/ZnO transparent conductive films

ZnO/Cu/ZnO transparent conductive thin films were prepared by RF sputtering deposition of ZnO target and DC sputtering deposition of Cu target on n-type (001) Si and glass substrates at room temperature. The morphology, structure, optical, and electrical properties of the multilayer films were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV/Vis spectrophotometer, and Hall effect measurement system. The influence of Cu layer thickness and the oxygen pressure in sputtering atmosphere on the film properties were studied. ZnO/Cu/ZnO transparent conductive film fabricated in pure Ar atmosphere with 10 nm Cu layer thickness has the best performance: resistivity of 2.3×10-4 Ω·cm, carrier concentration of 6.44×1016cm-2 , mobility of 4.51cm2·(V·s)-1 , and acceptable average transmittance of 80 % in the visible range. The transmittance and conductivity of the films fabricated with oxygen are lower than those of the films fabricated without oxygen, which indicates that oxygen atmosphere does not improve the optical and electrical properties of ZnO/Cu/ ZnO films.     

不同氮分压下磁控溅射ZrN对钛/瓷结合的影响

探讨不同氮分压下磁控溅射氮化锆(ZrN)涂层对纯钛与低熔瓷粉(Vita钛瓷粉系统)结合强度的影响。60个纯钛基片随机分为1个对照组和3个实验组。实验组分别在不同氮分压下(Ta组1.0×10-2Pa,Tb组5.0×10-2Pa和Tc组10.0×10-2Pa)溅射沉积ZrN涂层。纯钛试样经表面处理后在烤瓷炉中进行烧结。用XRD检测到ZrN立方新相。万能试验机测试钛瓷试样三点抗弯强度,对照组为(26.67±0.88)MPa,实验组分别为:Ta(49.41±0.55)MPa,Tb(54.55±0.69)MPa和Tc(46.24±0.53)MPa,四组间差别均有统计学意义(P<0.05)。SEM观察表明,实验组钛/瓷结合良好,钛基底残留的瓷断面数量较多,面积较大。不同氮分压下溅射沉积的ZrN涂层对钛/瓷结合的增强程度有所不同,5.0×10-2Pa下钛/瓷结合增强最为明显。     

Use of optical absorption spectroscopy for the characterization of an Ar−Ti magnetron discharge

The density of ground state and metastable Ti atoms were measured in a magnetron sputtering reactor with a 10 cm diameter Ti target by using resonant optical absorption spectroscopy. Experiments were conducted under various discharge parameters, namely the discharge current (0.2 A to 1.2 A) and the distance from the target (2 cm to 12 cm) under two working pressures (0.5 Pa and 4 Pa). The results were compared with previous results for a smaller magnetron source with a 5 cm diameter target. The Ti densities were as follows: [Ti]≈10¹¹ cm⁻³, [Ti_m]=10¹⁰ to 10¹¹ cm⁻³ for 0.5 Pa and [Ti]≈[Ti_∞]=10¹⁰ to 10¹² cm⁻³ for 4 Pa. The portion of Ti metastables in the discharge increases by a factor of approximately 2 as the working pressure increases.     

Influence of oxygen partial pressure on properties of N-doped ZnO films deposited by magnetron sputtering

N-doped ZnO films were radio frequency(RF)sputtered on glass substrates and studied as a function of oxygen partial pressure(OPP)ranging from 3.0×10-4 to 9.5×10-3 Pa.X-ray diffraction patters confirmed the polycrystalline nature of the deposited films.The crystalline structure is influenced by the variation of OPP.Atomic force microscopy analysis confirmed the agglomeration of the neighboring spherical grains with a sharp increase of root mean square(RMS)roughness when the OPP is increased above 1.4×10-3 Pa.X-ray photoelectron spectroscopy analysis revealed that the incorporation of N content into the film is decreased with the increase of OPP,noticeably N 1s XPS peaks are hardly identified at 9.5×10-3 Pa.The average visible transmittance(380-700 nm) is increased with the increase of OPP(from～17%to 70%),and the optical absorption edge shifts towards the shorter wavelength.The films deposited with low OPP(≤3.0×10-4 Pa)show n-type conductivity and those deposited with high OPP(≥9.0×10-4 Pa)are highly resistive(105Ω·cm)     

Surface Modification of C17200 Copper-Beryllium Alloy by Plasma Nitriding of Cu-Ti Gradient Film

In the present work, a copper-titanium film of gradient composition was firstly fabricated by the dual magnetron sputtering through power control and plasma nitriding of the film was then conducted to modify C17200 Cu alloy. The results showed that the prepared gradient Cu-Ti film by magnetron sputtering was amorphous. After plasma nitriding at 650 °C, crystalline Cu-Ti intermetallics appeared in the multi-phase coating, including CuTi₂, Cu₃Ti, Cu₃Ti₂ and CuTi. Moreover, even though the plasma nitriding duration of the gradient Cu-Ti film was only 0.5 h, the mechanical properties of the modified Cu surface were obviously improved, with the surface hardness enhanced to be 417 HV_0.01, the wear rate to be 0.32 × 10^?14 m³/Nm and the friction coefficient to be 0.075 at the load of 10 N, which are all more excellent than the C17200 Cu alloy. In addition, the wear mechanism also changed from adhesion wear for C17200 Cu substrate to abrasive wear for the modified surface.     

高功率脉冲反应磁控溅射CrNx涂层的放电特性与组分结构

高功率脉冲反应磁控溅射技术具有放电等离子密度高、溅射材料离化率高和绕镀性好的特点,已被广泛用于金属氮化物强化涂层的设计制备,但受沉积过程实时在线诊断困难,决定涂层结构性能的关键等离子体特性尚不清晰。基于自主研制的高功率脉冲磁控溅射装备,采用 Langmuir 探针研究不同 N₂流量下 CrN_x涂层的反应等离子体放电特性与组分结构变化。固定溅射功率为 3 kW,随着 N₂流量从 10 mL / min 增加至 75 mL / min,放电峰值功率密度和电子能量分布函数中的高能电子比例均呈现先上升后降低趋势,在 55 mL / min N₂流量时达到最高值,其峰值功率密度为 320 W / cm² 。分析表明,当通入过量 N₂时,靶中毒程度加剧,因表面生成 CrN_x化合物的二次电子发射系数低于 Cr,近基体区电子密度从 3.9×1017 / m³逐渐下降至 2.2×1017 / m³ ,低密度离子入射降低了沉积粒子的热扩散迁移长度,使得涂层呈现 CrN(220)晶面择优柱状生长。     

靶材用钨铜复合材料的制备工艺

在真空条件下,采用高温烧结钨骨架后渗铜工艺制备靶材用钨铜复合材料,研究烧结温度对钨坯及钨铜复合材料组织与性能的影响.结果表明:随着烧结温度的提高,钨颗粒间逐渐由点接触扩大为面接触,烧结颈逐渐长大,同时孔隙不断缩小并趋于球形,钨骨架和钨铜复合材料相对密度及硬度不断增加,而钨铜复合材料的电导率不断下降.当烧结温度为1950 ℃时,钨骨架和钨铜复合材料的相对密度分别达到74.8%和96.9%的最高值;钨铜复合材料的硬度(HB)达最大值2520 MPa,而电导率则降低到36.6IACS%,其中氧含量仅为4×10-6,氮含量为3×10-6.     

Fabrication, thermal stability and microhardness of sputtered Ni–P–W coating

Ternary Ni–P–W alloy coating was fabricated by the RF magnetron sputtering technique with dual targets of electroless nickel alloy and tungsten metal. The composition of both the alloy deposited and the sputtered targets were evaluated by electron probe microanalysis. The homogeneity of Ni–P targets fabricated by electroless nickel plating on copper plates was revealed from cross-sectional line profile analysis. Transitions in microstructure, in terms of the tungsten content in the as-deposited alloy deposit, were discussed using X-ray diffraction analysis. Results of microhardness tests showed that the surface hardness could be engineered by controlling the composition and microstructure in the Ni–P–W coating. A relatively high microhardness of approximately 1900 HK was observed for the ternary coating with high tungsten contents of 65 wt.%. The thermal stability could be enhanced by addition of tungsten into the deposit compared to the binary Ni–P sputtered coating.     

Thermomechanical properties of TiC particle-reinforced tungsten composites for high temperature applications

Tungsten and tungsten alloys are widely used in high temperature environments where arc ablation or mechanical deformation and damage are the main sources of materials failure. For high temperature critical applications in thermomechanical environments, however, the low strength limits the use of tungsten and tungsten alloys. Hence, new tungsten based materials with good high temperature thermomechanical properties need to be developed in order to extend the use of tungsten. TiC particle-reinforced tungsten based composites (TiC_p/W) were fabricated by hot pressing at 2000 °C, 20 MPa in a vacuum of 1.3×10⁻³ Pa. The composites were examined with respect to their thermophysical and mechanical properties at room temperature and at elevated temperature. Vickers hardness and elastic modulus increased with increasing TiC content from 0 to 40 vol.%. The highest flexural strength, 843 MPa, and the highest toughness, 10.1 MPa m^1/2, of the composites at room temperature were all obtained when 20 vol.% TiC particle were added. As the test temperature rose, the flexural strength of the TiC_p/W composites firstly increased and then decreased, except in the monolithic tungsten. The highest strength of 1155 MPa was measured at 1000 °C in the composite containing 30 vol.% TiC particles. The strengthening effect of TiC particles on the tungsten matrix is more significant at high temperatures. With the addition of TiC particles, the thermal conduction of tungsten composites was drastically decreased from 153 W m⁻¹ K⁻¹ for monolithic W to 27.9 W m⁻¹ K⁻¹ for 40 vol.% TiC_p/W composites, and the thermal expansion was also increased. The new composites are successfully used to make high temperature grips and moulds.     

Environmental embrittlement of two-phase Fe30Ni20Mn35Al15

It is shown that the ductility of lamellae-structured Fe₃₀Ni₂₀Mn₃₅Al₁₅ (in at. %), which consists of B2 and f.c.c. phases, is influenced by testing environment. Tensile tests performed in air at strain rates ranging from 3 × 10^?6 to 3 × 10^?1 s^?1 showed that the elongation to fracture and ultimate tensile strength (UTS) increased with increasing strain rates below 3 × 10^?3 s^?1, and were independent of strain rate at ～10.5% and 840 MPa for strain rates ≥ 3 × 10^?3 s^?1. In order to understand this strain-rate sensitive behavior, tensile tests were also performed in either dry oxygen or 4% hydrogen + nitrogen at different strain rates. The elongation and UTS in oxygen were insensitive to strain rate and close to those tested at 3 × 10^?3 s^?1 in air, whereas the elongation in hydrogen was 4% for strain rates ≤3 × 10^?3 s^?1 and increased to ～10.8% at 3 × 10^?1 s^?1. The reduction of ductility in air and hydrogen-charged environment at low strain rate is attributed to hydrogen embrittlement.     

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%.     

Growth and characterization of BaLiF3 single crystal as a new optical material in the VUV region

The growth of undoped BaLiF₃ (BLF) single crystals, a candidate for window material in the vacuum-ultraviolet (VUV) region, was carried out in a Czochralski system under CF₄ atmosphere. BLF single crystals 1 inch in diameter were obtained and characterized. The thermal expansion coefficient of the BLF single crystal along the 〈100〉-axis was 3.33×10⁻⁵ K. The distribution of birefringence along the 〈100〉-axis was in the order of 10⁻⁷. The absorption edge of BLF was determined to be 123 nm, showing high potential as an optical window material in the VUV region.     

反应磁控溅射沉积纳米多孔BiVO4薄膜光催化剂:总压力和基底的影响

使用脉冲直流电源、金属Bi和V靶材,在氩气和氧气气氛保护下,通过反应磁控溅射法在不同基板上沉积纳米多孔BiVO4薄膜,然后在空气中进行后退火处理,形成具有光敏性的单斜白钨矿晶体.研究总压力和基底对薄膜晶体结构、形貌、显微组织、光学和光催化性能的影响.结果表明,在石英玻璃基底上沉积的单斜白钨矿结构于250℃开始结晶,薄膜...     

Fabrication and characterization of ITO thin films on heat-resistant transparent flexible clay films

Transparent conductive indium tin oxide (ITO) thin films were deposited on transparent flexible clay films with heat resistant and high gas barrier properties by rf magnetron sputtering. The electrical, structural, and optical properties of these films were examined as a function of deposition temperature. A lowest resistivity of 4.2 × 10^− 4 Ωcm and an average transmittance more than 90% in the visible region were obtained for the ITO thin films fabricated at deposition temperatures more than 300 °C. It was found that ITO thin films with low resistivity and high transparency can be achieved on transparent flexible clay film using conventional rf magnetron sputtering at high temperature, those characteristics are comparable to those of ITO thin films deposited on a glass substrate.     

Fabrication and magnetic properties of NiFe-ZnO nano-granular films

Excellent soft magnetic and high frequency properties were obtained successfully in the (Ni75Fe25 )x(ZnO)1-x granular films fabricated on the glass substrate by RF magnetron oblique sputtering. The microstructure, mag- netic and high frequency properties were investigated systematically. High resolution transmission electron micrographs show that the film consists of fcc Ni75Fe25 particles uniformly embedded in an amorphous insulating matrix ZnO with particle size a few nanometers. The (Ni75Fe25 ) x(ZnO)1-x films exhibit excellent soft magnetic properties in a wide x range from 0.50 to 0.80 with coercivity not exceeding 5×10-4T, which is ascribed to the exchange coupling between magnetic particles. Especially for the sample with x = 0.64, coercivities in hard and easy axes are 5.0×10-5 and 3.6×10-4 T, respectively, and the electric resistivity ρ reaches 1,790 μΩ·cm. The dependence of complex permeability u = u’ - ju" on frequency f shows that the real part u’ is more than 130 below 500 MHz, and the ferromagnetic resonance frequency fr reaches 1.32 GHz, implying the promising for high frequency application.     

Ti/TiSiNO Multilayers Fabricated by Co-sputtering

Multilayer coatings of titanium/ titanium silicon oxynitride (Ti/TiSiNO) were fabricated on stainless steel 434-L substrates by sputtering technique using Ti and TiSiO targets. The multilayers were formed by alternately and simultaneously introducing and suspending a 4-sccm flow of nitrogen together with an interchange of targets, during different time periods of 1.0, 2.0, 3.0 and 4.0 min; thus, we obtained intervals of different thickness by alternating the target (Ti) and using only argon, and later with both targets (Ti + TiSiO) and the two gases (Ar + N₂). The final thickness was within a range of 0.4-0.8 μm, depending on the number of multi layers obtained by means of glow discharge optical emission spectroscopy. The structure, topography, color, durability and nanofriction were analyzed in accordance with the growth parameters used. It was found that the values of hardness depend on the number of layers deposited. The greatest number of layers, 48 of them, was obtained with a time period of 1 min, thereby attaining the maximum value of hardness and the minimum value for both the friction coefficient and the RMS, with 31 GPa, 7.42 × 10^?3 and 0.17 nm, respectively. The phases found correspond to Ti₂N, Si₃N₄, rutile phase of TiO₂ and Ti. The TiO₂ phase was corroborated with Raman dispersion spectroscopy. The color of the coatings was affected by variation in the working pressure, which varied because of the internal process of reactive sputtering.     

On the Change in Work Hardening Characteristics of Molybdenum Polycrystals Due to Natural Aging

Strips of 99.95 at.% Mo polycrystals annealed at 700 °C as well as the ones annealed and then aged for 6 months at room temperature were deformed in tension at various strain-rates in the range 2.1 × 10⁻⁴ to 4.2 × 10⁻³ s⁻¹ till fracture. It is found that natural aging of the annealed specimens for 6 months leads to 20-30% reduction in the yield stress (YS), 18-22% reduction in the ultimate tensile strength (UTS), and 72-76% reduction in the ductility, i.e. the tensile strain ε_max corresponding to UTS, depending on the value of [\upvarepsilon \dot] \dot{\upvarepsilon } in the tensile strain-rate range referred to. Data analysis in terms of the kink-pair nucleation model of flow stress shows that the reduction in YS of the aged Mo specimens is a consequence of lowering of the Peierls energy per interatomic spacing along the length of screw-dislocation segments trapped in the Peierls valleys on the migration of point defects to the dislocation cores during the course of natural aging. The reduction in UTS and ε_max is attributed to the variation in the relative contribution of the processes of dislocation multiplication and annihilation together with the reduction in the Peierls stress of the metal.     

The compression stress-strain behavior of Sn-Ag-Cu solder

The yield-stress behavior was investigated for the 95.5Sn-4.3Ag-0.2Cu (wt.%), 95.5Sn-3.9Ag-0.6Cu, and 95.5Sn-3.8Ag-0.7Cu ternary lead-free solders using the compression stress-strain test technique. Cylindrical specimens were evaluated in the as-cast or aged (125°C, 24 h) condition. The tests were performed at −25°C, 25°C, 75°C, 125°C, and 160°C using strain rates of 4.2×10⁻⁵s⁻¹ or 8.3×10⁻⁴s⁻¹. Specially designed Sn-Ag-0.6Cu samples were fabricated to compare the yield stress of the dendritic microstructure versus that of the equiaxed microstructure that occurs in this alloy. For more information, contact P.T. Vianco, Sandia National Laboratories, MS 0889, PO Box 5800, Albuquerque, New Mexico 87185; (505) 844-3429; e-mail ptvianc@sandia.gov.     

Effects of growth temperature on μc-Si:H films prepared by plasma assistant magnetron sputtering

Hydrogenated microcrystalline silicon thin films (μc-Si:H) were deposited by plasma assistant magnetron sputtering in Ar-H2 gas mixture. The effects of growth temperature from 150 to 450 ℃ on properties of deposited Si films were investigated at two different hydrogen diluted gases with [H2]/([Ar]+[H2]) of 10％and 50％at 3 Pa. The crystallinity of Si films examined by Raman scattering exhibited higher degradation by lowering growth temperature from 250 to 150 ℃ in low hydrogen diluted gas of 10％ than that in high hydrogen diluted gas of 50％. The IR absorption band around 845 and 890 cm-1 as well as calculated concentration of bonded hydrogen showed more obvious decrease of samples deposited in low hydrogen diluted gas of 10％ than that in high hydrogen diluted gas of 50％. The optical band gasps of both groups of samples measured by ultraviolet-visible optical absorption were decreased with increasing temperature in both gas conditions.