Structure analysis of sputter-coated and ion-beam sputter-coated films: a comparative study

Gold, platinum and tungsten films were deposited by low energy input (7 mA, 450 V), or high deposition rate (80 mA, 1500 V), diode sputter coating and by ion beam sputter coating. Film structures on Formvar coated grids and on the surface of coated erythrocytes, resin embedded, sectioned, and recorded at high magnification in a TEM were compared using computer-assisted measurements and analysis of film thickness and grain size. The average grain size of the thinnest gold and platinum films was relatively independent of the mode or rate of deposition but as the film thickness increased, significant differences in grain size and film structure were observed. Thick platinum or gold films deposited by low energy input sputter coating contained large grain size and electron transparent cracks; however, more even films with narrower cracks but larger grain size were produced at high deposition rates. Ion beam sputter coated gold had relatively large grain size in 10 nm thick films, but beyond this thickness the grains coalesced to form a continuous film. Platinum films deposited by ion beam sputter coating were even and free of electron transparent cracks and had a very small grain size (1–2 nm), which was relatively independent of the film thickness. Tungsten deposition either by low energy input or ion beam sputter coating resulted in fine grained even films which were free of electron transparent cracks. Such films remained granular in substructure and had a grain size of about 1 nm which was relatively independent of film thickness. Tungsten films produced at high deposition rates were of poorer quality. We conclude that thick diode sputter coated platinum and gold films are best deposited at high deposition rates provided the specimens are not heat sensitive, the improvement in film structure being more significant than the slight increase in grain size. Thick diode or ion beam sputter coated gold films should be suitable for low resolution SEM, and thin discontinuous gold films for medium resolution SEM. Diode sputter coated platinum should be suitable for medium resolution SEM and ion beam sputter coated platinum for medium and some high resolution SEM. 1–5 nm thick tungsten films, deposited by low energy input or ion beam sputter coating should be suitable for high resolution SEM, particularly where contrast is of less importance than resolution.     

Optimum film thickness of thin metallic coatings on silicon substrates for low load sliding applications

The frictional behaviour of thin metallic films on silicon substrates sliding against 52100 steel balls is presented. The motivation of this work is to identify an optimum film thickness that will result in low friction under relatively low loads for various metallic films. Dry sliding friction experiments on silicon substrates with soft metallic coatings (silver, copper, tin and zinc) of various thickness (1–2000 nm) were conducted using a reciprocating pin-on-flat type apparatus under a controlled environment. A thermal vapour deposition technique was used to produce pure and smooth coatings. The morphology of the films was examined using an atomic force microscope, a non-contact optical profilometer and a scanning electron microscope. Following the sliding tests, the sliding tracks were examined by various surface characterization techniques and tools. The results indicate that the frictional characteristics of silicon are improved by coating the surface with a thin metallic film, and furthermore, an optimum film thickness can be identified for silver, copper and zinc coatings. In most cases ploughing marks could be found on the film which suggests that plastic deformation of the film is the dominant mode by which frictional energy dissipation occurred. Based on this observation, the frictional behaviour of thin metallic coatings under low loads is discussed and friction coefficients are correlated with an energy based friction model.     

Nano-mechanical and tribological characteristics of ultra-thin amorphous carbon film investigated by afm

The mechanical as well as tribological characteristics of coating films as thin as a few nm become more crucial as applications in micro-systems grow. Especially, the amorphous carbon film has a potential to be used as a protective layer for micro-systems. In this work, quantitative evaluation of nano-indentation, scratching, and wear tests were performed on the 7nm thick amorphous carbon film using an Atomic Force Microscope (AFM). It was shown that AFM-based nano-indentation using a diamond coated tip can be feasibly utilized for mechanical characterization of ultra-thin films. Also, it was found that the critical load where the failure of the carbon film occurred was about 18μN by the ramp load scratch test. Finally, the wear experimental results showed that the quantitative wear rate of the carbon film ranged 10^-9~10^-8 mm³/N cycle. These experimental methods can be effectively utilized for a better understanding the mechanical and tribological characteristics at the nano-scale.     

基于Au-Ag复合膜的光纤表面等离子体共振传感器理论仿真研究

为增强基于Ag膜光纤表面等离子体共振(SPR)传感器的抗氧化能力,可将Au膜镀于Ag膜表面。利用TFCalc软件对不同厚度Ag膜和Au-Ag复合膜的光纤SPR传感特性进行理论仿真研究。仿真结果表明:光纤SPR吸收峰显著依赖于Ag膜厚度,当Ag膜厚度由40nm逐渐增加到80nm时,共振吸收峰的半峰全宽逐渐减小,且共振波长随Ag膜厚度的增大而减小,共振波长变化范围较小,仅为7nm左右;Au膜的引入对共振吸收峰反射率影响不大,不同厚度Au-Ag复合膜的SPR共振波长随Au膜厚度的增大而增大。     

应用SiC反射镜表面改性技术提高TMC光学系统信噪比

为了消除SiC反射镜的固有缺陷,提高反射式光学系统的信噪比,使用SiC表面改性技术对同轴三反射(TMC)光学系统的SiC反射镜进行了处理.首先,应用等离子体辅助沉积(PIAD)技术沉积了一层Si改性层,接着对改性层进行精密抛光,然后在反射镜表面镀制Ag膜和增强膜,最后获得了表面改性对TMC光学系统信噪比的影响.Wyko轮廓仪测试表明,SiC反射镜的粗糙度R_a由10.42 nm降低到了0.95 nm;镀制高反射膜后,主镜、次镜、三镜及折叠镜在0.5～0.8 μm可见光波段的反射率＞98%.计算结果表明,应用了表面改性技术后TMC反射式光学系统的信噪比提高了5%以上,说明SiC表面改性技术是一种提高TMC光学系统信噪比的有效方法.     

Plasmon transmissivity and reflectivity of narrow grooves in a silver film

Surface plasmon (SP) reflectivity and transmissivity of narrow grooves in silver films are studied. The SP source is the probe of a scanning near-field optical microscope. Locally detected leakage radiation from the SP provides detailed information on the paths of SP propagation, in particular the influence of perturbations. Global detection provides representative average data on the SP properties of a given metal film and its structures. A groove of 200 nm width, for instance, reflects/transmits about 15%/80% of 'blue–green' SP radiation at normal incidence.     

紫外激光单脉冲辐照损伤金属薄膜的数值模拟研究

针对不同厚度的镍膜以及金膜,利用多物理场耦合分析软件COMSOL Multiphysics研究了波长248nm、矩形脉冲宽度14ns激光辐照损伤阈值随膜厚变化的物理过程。本研究与他人的理论计算和实验测得的结果基本一致,研究表明:在高强度单脉冲激光均匀辐照下,金属薄膜表面的损伤主要是由于激光能量在其材料内部的沉积而导致的热效应引起的;当金属薄膜的厚度小于其光学吸收长度时(镍膜厚度<8nm,金膜厚度<12nm),其熔融损伤阈值随着薄膜厚度的增加而减小;当薄膜厚度大于光学吸收长度而小于其热扩散长度时(镍膜厚度8~730nm,金膜厚度12~1 050nm),其熔融损伤阈值随薄膜厚度增加而线性增加;当薄膜厚度大于其热扩散长度时(镍膜厚度>730nm,金膜厚度>1 050nm),其熔融损伤阈值随薄膜厚度的增大基本保持不变。     

Growth of low resistivity and high transparency boron-doped zinc oxide film by pulse laser deposition

0.5 wt% boron-doped zinc oxide (BZO) films were fabricated by utilizing pulse laser deposition under different growth temperature ranged from 250 to 450 °C. The effect of the growth temperature on the structural, optical, and electrical properties was investigated and discussed. The crystal structure and orientation of BZO thin films were examined by X-ray diffraction. All of the BZO films under various growth temperatures had strong c-axis (002)-preferred orientation. Optical transparency was high (>80%) over a wide spectral range from 400 nm to 700 nm, and the optical bandgap value of BZO are found to be in the range from 3.18 to 3.47eV. According to the experimental data, the resistivity of the BZO film was optimized at ~1.13 × 10⁻³ Ω-cm and significantly influenced by the growth temperature.     

Role of the Transfer Film on the Friction and Wear of Metal Carbide Reinforced Amorphous Carbon Coatings During Run-in

The relationship between friction, wear, and transfer films of three metal carbide-reinforced amorphous carbon coatings (TiC/a:C, TiC/a:C–H, and WC/a:C–H), sometimes referred to as metal-doped diamond-like carbon coatings, has been investigated. Tribological tests were performed in an in situ tribometer with sapphire or steel hemispheres run against coated flats in dry or ambient air. The sliding contact interface was observed and recorded by optical microscopy during reciprocating sliding tests. The friction and wear behavior during run-in depended on the number of sliding cycles to form a stationary transfer film on the hemisphere. Stationary transfer films formed rapidly (within ten cycles) and the friction coefficient fell to 0.2 (ambient air) or 0.1 (dry air), except with sapphire against WC/a:C–H in dry air; with the latter, a stationary transfer film required nearly 100 cycles to form, during which the friction remained high and the wear rate was from 10 to 100 times higher than the other two coatings. For all coatings, three velocity accommodation modes (VAM) were observed from run-in to steady-state sliding and were correlated with the friction and wear behavior. The delayed adherence of the transfer film to sapphire from WC/a:C–H coatings in dry air is discussed in terms of equilibrium thermochemistry. Friction and wear behavior during run-in, therefore, depended on transfer film adherence to the hemisphere and the VAM between transfer films and the coating.     

Plasmon transmissivity and reflectivity of narrow grooves in a silver film

Surface plasmon (SP) reflectivity and transmissivity of narrow grooves in silver films are studied. The SP source is the probe of a scanning near-field optical microscope. Locally detected leakage radiation from the SP provides detailed information on the paths of SP propagation, in particular the influence of perturbations. Global detection provides representative average data on the SP properties of a given metal film and its structures. A groove of 200 nm width, for instance, reflects/transmits about 15%/80% of 'blue-green' SP radiation at normal incidence.     

基于自适应模拟退火算法的薄膜特性参数计算方法研究

提出了根据测量得到的待测薄膜的透射率数据,采用全局优化算法—自适应模拟退火算法结合共轭梯度算法求解薄膜的光学特性参数。并对T a2O5单层薄膜的厚度及折射率进行测量计算。实验结果表明,计算得到的光学特性参数值与实测结果相一致,厚度误差小于3nm,在540nm处折射率误差小于0.02。该方法具有操作简单、无损测量、计算速度快、精度高等优点,具有相当的实用性。     

金属纳米线阵列红外偏振器

本文用电磁场理论推导了多排金属纳米线有序阵列的光学损耗表达式，并进行了数值模拟。采用电化学沉积工艺将金属银电镀到氧化铝的孔中，得到含银纳米线氧化铝膜有序阵列复合结构，测量了含银纳米线氧化铝膜的光学损耗。理论和实验研究表明，含银纳米线氧化铝膜有序阵列的光学损耗显著依赖于光的偏振方向，在红外波段表现出良好的偏振特性，是一种新型红外微偏振器。     

空间RB-SiC反射镜的表面离子辅助镀硅改性技术

针对空间用RB-SiC材料由Si\SiC两相结构引起的光学表面缺陷问题,提出了表面离子辅助沉积（IAD）硅膜的改性新方案以优化RB-SiC光学表面反射率。对厚度为10µm的IAD-Si改性层的主要性能研究显示：IAD-Si膜层为非结晶结构,能够提供较好的抛光表面,在77K-673K的热冲击下膜层稳定性良好。以Si膜的抛光机理为依据对IAD-Si改性层进行了大量抛光工艺实验和表面质量测试,给出了关键的抛光工艺参数和实验结果。通过表面IAD-Si改性及本文提出的改性层超精加工技术能够在反射镜表面得到面形精度的RMS值低于1/20λ(λ=632.8nm)且表面粗糙度的RMS值低于0.5nm的超光滑表面;与改性前相比,反射镜改性层抛光表面在360-1100 nm 波段的反射率提高了4.5%以上。     

SPR谱仪的研制及在磁光复合薄膜测试中的应用

针对SPR增强磁光效应研究中复合金属薄膜结构的SPR激发测试,研制了一套角度扫描型SPR谱仪。通过巧妙的结构设计和运动控制,使得角度扫描过程中样品测试点始终处于棱镜底面样品基片的中心,保证了测试过程的一致性。对50nm金膜的重复性测验表明SPR谱仪具有较高的重复性和稳定度。利用搭建的SPR谱仪对磁光复合薄膜的测试结果表明,在制备的样品中,Au(15nm)/Co(5/10nm)/Au(5nm)复合结构是磁光等离子体系研究的最佳平台。     

Quantification of the Thickness of Carbon Transfer Films Using Raman Tribometry

A method to quantify transfer film thickness of diamond-like nanocomposite (DLN) coatings during sliding is presented. Previously, we showed that as the transfer film thickened then thinned, Raman carbon spectra evolved from that of the coating, to the transfer film, then back again to the coating. In this paper, the transfer film thickness is quantified using Raman spectra with stylus profilometry and a light-scattering model based on Beer's Law. Non-linear least-square fits of Raman intensity versus thickness data of several transfer films gave an optical mean free path of 500 nm. The model was also used to quantify transfer film thickness between 10 and 960 nm from the Raman intensity (at a given frequency) of the combined coating–transfer film spectrum. Finally, the model was applied to in situ spectra during sliding to establish a thickness at which a transfer film wore through causing a rise in friction.     

Film Forming and Friction Properties of Overbased Calcium Sulphonate Detergents

The film-forming and friction properties of overbased calcium sulphonate (OBCaSu) detergents in rolling–sliding, thin film, lubricated contact have been investigated. All of the commercial detergents studied form thick, solid-like, calcium carbonate films on the rubbed surfaces, of thickness 100–150 nm. The films have a pad-like structure, interspersed by deep valleys in which practically no film is present. These films have the effect of increasing friction in intermediate speed conditions, an effect which is believed to occur because the pad structure of the film inhibits fluid entrainment and thus postpones the formation of an EHD film to higher entrainment speeds. Large differences were noted between the boundary friction coefficients of the various detergents tested. Two of them gave very low boundary friction coefficients, in the range 0.06–0.08, while the other two gave considerably higher friction. These differences are believed to originate from differences in the structures of the alkyl chains in the sulphonate detergent molecules. The films formed by OBCaSu detergents can be removed very effectively by treatment with EDTA solution and this shows that the films are effective in preventing wear.     

Assessment of adhesion between thin film and silicon based on a scratch test

Thin film coatings are commonly utilized to prevent wear, modify surface properties, and manipulate the frictional behavior of various mechanical systems. The behavior of a coating has a direct effect on the life as well as performance of the system. However, the coating itself is subject to damage, and the quality of the coating is related to the adhesion characteristics between the coating and the substrate. Therefore, a quantitative assessment of the adhesion properties of thin film is important to guarantee the reliability of not only the thin film but also the mechanical system. In this study, ramp loading scratch tests were performed to assess the adhesion characteristics of Ag and ZnO thin films coated on a silicon wafer. Silver thin film, deposited by sputtering, and ZnO thin film, fabricated by a sol-gel method, were used as scratch specimens. Scratch tests using a diamond tip were performed with a continuously increasing normal force. During the scratch test, the normal and frictional forces were monitored to assess the integrity of the film. The Benjamin and Weaver model commonly used for obtaining the horizontal force during the scratching of films coated on a substrate showed large discrepancies with the experimental results. In this work, the model was modified with a plowing term to minimize the difference between the experimental and theoretical results. Using the modified model, the experimental results could be predicted with an accuracy of about 10%.     

高折射率镀膜聚合物波导传感器的制备

为了提高利用倏逝波传感的光纤传感器的灵敏度问题,仿真并验证了一种基于高折射率镀膜的光纤传感器.首先两根光纤之间利用激光诱导波导自行成技术形成聚合物波导,并在波导表面镀上一层高折射率Ta2O5薄膜以增强波导表面倏逝波强度,从而增加传感器灵敏度.根据聚合物波导制备结果,使用COMSOL Multiphysics?软件对Ta...     

Mirrorlike pulsed laser deposited tungsten thin film

Mirrorlike tungsten thin films on stainless steel substrate deposited via pulsed laser deposition technique in vacuum (10(-5) Torr) is reported, which may find direct application as first mirror in fusion devices. The crystal structure of tungsten film is analyzed using x-ray diffraction pattern, surface morphology of the tungsten films is studied with scanning electron microscope and atomic force microscope. The film composition is identified using energy dispersive x-ray. The specular and diffuse reflectivities with respect to stainless steel substrate of the tungsten films are recorded with FTIR spectra. The thickness and the optical quality of pulsed laser deposition deposited films are tested via interferometric technique. The reflectivity is approaching about that of the bulk for the tungsten film of thickness ～782 nm.