Hall Effect due to channeled pinning potential in Nb thin films

We have studied the Magnetoresistance and Hall Effect in Nb superconducting thin films with triangular arrays of holes. Three different arrays of defects have been prepared with different orientations with respect to the current. Because vortex dynamics in the mixed state in type-II superconductors is strongly influenced by the pinning centers, a channeled pinning landscape is formed by the pinned vortices. It is suggested that the motion of interstitial vortices has great influence by the channel. When vortices propagate through these arrays, both the longitudinal and transversal voltages show cusp-like anomalies at matching fields. Vortices can be guided by the channel formed between pinned vortices. The longitudinal voltages are the same when there is a sign change of magnetic field. The longitudinal and transversal Hall voltages are dependent on the rotating angle of the arrays.     

Modified equation of state for thin 4He films

A modified equation of state for thin films of superfluid helium is used to analyze experimental results on third sound propagation. The combined effects of this modification and a consideration of fluctuation phenomena serve to improve markedly the comparison between theory and experiment.On leave from the Technion-Israel Institute of Technology, Haifa, Israel.     

Continuous spectrum in optical absorption for granular thin films

We discuss in a rigorous mathematical way the quasi-static eigenmodes for arbitrarily shaped particles (metallic islands) deposited onto a transparent substrate. The usual ellipsoid model predicts only one discrete resonance for each direction of the applied electric field. It is shown that the resonance spectrum for particles having an edge or even a single point in contact with the substrate must present a continuous part in addition to a possible set of discrete resonances.Assuming that the dihedral angle remains constant along the whole edge of the particle, we determine the position of the continuous spectrum. The particular problem of a truncated cylinder lying on a substrate, for which an exact solution can be obtained by conformal mapping, allows us to verify the general theory presented here and leads to a comparison with previous calculations for hemispherical particles.     

Characterization of photoactive polymer thin films using transmission spectrum

There are many different methods applied to obtain the optical constants of thin films using transmission spectrum, none of them applied to photoactive polymer thin films. The aim of this work is to find the suitable method for routine measurements of photoactive polymer thin films. In order to achieve this goal, different methods are applied to simulated thin films of known optical constants to compare their accuracies, hence choosing the most suitable method for studying the photoactive polymer thin films. It is found that the fitting methods are not suitable for photoactive polymer thin films while numerical solution of two independent transmission measurements is suitable for such films, so poly methy1 methacrylate (PMMA) films doped with different concentrations of photoactive unit Disperse Red 1 (DSR1) are characterized using this method. The refractive index of PMMA doped with 0.2% of DSR1 (1 g PMMA, 2 mg DSR1) is found to be 1.534 with error 0.656% at λ = 630 nm. It is also found that the refractive index of photoactive polymer thin films increases linearly with increasing photoactive unit up to concentration 0.25%.     

类金刚石薄膜的制备及其电阻率、光谱特性研究

采用射频磁控溅射法在单晶硅表面制备了类金刚石薄膜;对薄膜的电阻率进行了测量,研究了薄膜的溅射工艺参数,采用拉曼光谱、原子力显微镜、扫描电镜分析了薄膜的结构、表面形貌以及薄膜的截面形貌.结果表明,薄膜中含有sp2、sp3杂化碳原子,拉曼谱高斯拟合峰的ID/IG为3.67;薄膜的电阻率达6×103 Ωcm.最佳溅射气压在0.4 Pa左右,最佳溅射功率在140 W左右;薄膜的表面平整光滑,平均粗糙度低达0.17 nm;SEM形貌表明薄膜由大量大小均匀的碳颗粒组成,薄膜内部十分致密,与基底结合很好.     

Development of thickness measurement program for transparent conducting oxide thin films

The gallium doped zinc oxide has been one of the candidates for the transparent conducting oxide thin film electrode. It is not suitable to use a conventional light interference method to measure the thickness of the gallium doped zinc oxide thin film because the refractive index and extinction coefficient of the thin film is unknown during the optimization of the deposition conditions. In this paper, we report on the details of the film thickness program which uses the measured optical and electric properties and relationship between the plasma frequency and the optical constant of the film. The obtained film thickness of the prepared gallium doped zinc oxide thin film using the program was comparable with thicknesses measured by a cross-sectional analysis of the atomic force microscopy and the surface profiler. Moreover, the optical constant of refractive index and extinction coefficient of the film could also be estimated.     

A continuous electrical resistivity measurement in thin films

The continuous electrical resistivity measurement, while an interesting parameter is being changed, can be a useful tool for in-situ thin film analysis as most changes in films are accompanied by changes in the electrical resistivity. In-situ measurements in a tube furnace at atmospheric pressure during different heat treatments are presented for oxidation tracing in Cr films and the TiN/CrN multilayer and for detection of interactions in Ni/Si}, Ti/Si} and Ni/Al multilayers. Results of electrical resistivity measurements c correlated well with weight gain measurements, X-ray diffraction, Rutherford backscattering spectroscopy and Auger electron spectroscopy depth profiling. It is therefore shown that the measurement of the resistivity with its time and temperature derivatives can represent a useful basis for the application of other analytical methods.     

Photoacoustic measurement of thermal properties of TiN thin films

Titanium nitride (TiN) thin films were prepared by reactive DC magnetron sputtering under different nitrogen flow rates and at constant substrate temperature as well as at constant nitrogen flow rate and at different substrate temperatures. Photoacoustic measurement of the thermal properties of the films revealed that the thermal diffusivity and thermal conductivity of the TiN thin films are significantly lower than the bulk values and that the grain size of the films has substantial influence on the thermal properties of TiN thin films. The thermal conductivity of the films decreases with increasing nitrogen flow rates and increases with increasing substrate temperature. The above opposing behaviour in the thermal properties is found to be related to the microstructure, especially, the grain size of the films.     

A method for measurement of "Creep" in thin magnetic films

The "creep" phenomenon in thin magnetic films is measured using a field consisting of a static field parallel to the film's easy axis, and a high-frequency sinusoidal field along the transverse axis. A special field-gradient coil is used to establish a two-domain magnetization configuration in the film plane, and the Kerr magneto-optic effect is employed to measure the position of the disturbed domain wall. Measurements on Ni-Fe-Co and NiFe alloy films show the typically sharp threshold field below which there is no wall creep; nonuniform creep gives evidence for wall "pinning" phenomena. With the method described for field calibration and the simple form of fields employed, this procedure should be valuable in establishing comparative creep sensitivity data for films formed from different alloys or by different technologies.     

AgOx薄膜的形貌、光谱以及激光烧蚀研究

制备了不同氧分压比的AgOx薄膜,对其进行了原子力(AFM)形貌观察,发现分压比0.4时,薄膜的粗糙度最小,均匀性也最好.光谱性质表明:随着分压比的增加,存在着金属向半导体的转变;经过热处理后的共振吸收峰和扫描电(SEM)表明了金属银粒子的析出.不同激光功率下的烧蚀实验表明:在激光照射下存在着两记录(烧蚀)形态,一种是银粒子散布在其间的气泡型;另一种是形成中间烧蚀孔,银粒子在孔附近密集的破裂气泡型.     

导电薄膜电阻测量技术的可靠性研究

针对手提式薄膜方块电阻测试仪在使用中容易出现的问题,进行分析研究,提出了解决方案,并在实验中得到实现.研究的问题包括:电池供电的电压监测;探头完全与被测样品接触良好的检测;防止探针对被测样品造成电击穿;测量时自动进行量程转换等.     

Fourier analysis near-field polarimetry for measurement of local optical properties of thin films

We present measurements of the local diattenuation and retardance of thin-film specimens by using techniques that combine near-field scanning optical microscopy (NSOM) and a novel polarization-modulation (PM) polarimetry utilizing Fourier analysis of the detected intensity signal. Generally, quantitative near-field polarimetry is hampered by the optical anisotropy of NSOM probes. For example, widely used aluminum-coated pulled-fiber aperture probes typically exhibit a diattenuation near 10%. Our analysis of aperture diattenuation demonstrates that the usual techniques for nulling a PM polarimeter result in a nonzero residual probe retardance in the presence of a diattenuating tip. However, we show that both diattenuation and retardance of the sample can be determined if the corresponding tip properties are explicitly measured and accounted for in the data. In addition, in thin films (<100 nm thick), where the sample retardance and diattenuation are often small, we show how to determine these polarimetric quantities without requiring alignment of the fast and diattenuating axes, which is a more general case than has been previously discussed. We demonstrate our techniques by using two types of polymer-film specimens: ultrahigh molecular weight block copolymers (recently noted for their photonic activity) and isotactic polystyrene spherulites. Finally, we discuss how changes in the tip diattenuation during data collection can limit the accuracy of near-field polarimetry and what steps can be taken to improve these techniques.     

Method of measurement and analysis of texture in thin films

A method of measurement and analysis of texture in thin films is proposed. In this method, the incidence angle of the X-ray beam is low and is kept constant during the measurements. This requirement allows information to be obtained from a thin surface layer of the specimen. However, it limits the area on the pole figure from which data can be measured. Quantitative analysis of various factors and parameters which affect the X-ray penetration depth and the measured area of the pole figure is proposed. The proposed method was implemented and tested and the results obtained were used to calculate the crystal orientation distribution function.     

A pulse generation circuit for improved measurement of currenttransients in ferroelectric thin films

The design and construction of a circuit using Hg-wetted relays to deliver a high current (1 A) at high amplitude (±50 V) with short pulse rise and fall times (<1.5 ns) to a 50-Ω load resistor are presented. The pulse switching transient in a ferroelectric 0.52 PbZrO ₃-0.48 PbTiO₃ or PZT (52/48) thin-film sample using this circuit is compared with commercial pulse generators. Most importantly, the output of this Hg-wetted pulse generator is independent of the ferroelectric thin-film sample being probed, which is essential for comparing measured results     

Mechanical measurement of the residual stress in thin PVD films

A practical mechanical bending plate method is proposed to calculate the residual stress present in thin physical vapour deposition films. A thin circular foil of stainless steel is coated with TiN, using an unbalanced magnetron sputtering technique. Sectioning of this foil into narrow strips leads to an easily measurable radius of curvature. With the help of calculations based on the finite element method it is shown that, if the width-to-length ratio is small, the analytical formula of Senderoff is valid. Above a certain width-to-length ratio, serious errors in calculated stress values are introduced using Senderoff. The second part of this paper describes the influences of the deposition parameters of TiN on the residual stress in the coating. An increase of the bias voltage results in a higher compressive stress, varying from −4.2 to −7.2 GPa. Experiments with different substrate materials show that the growth stress is independent of the substrate material. The total residual stress present in the coating increases with a higher magnetron current and a lower working gas pressure.

There was excellent agreement between the results of the proposed method and X-ray diffraction (Seemann-Bohlin).     

基于光谱干涉椭偏法的薄膜厚度测量

薄膜厚度的测量在芯片制造和集成电路等领域中发挥着重要作用。椭偏法具备高测量精度的优点,利用宽谱测量方式可得到全光谱的椭偏参数,实现纳米级薄膜的厚度测量。为解决半导体领域常见的透明硅基底上薄膜厚度测量的问题并消除硅层的叠加信号,本文通过偏振分离式光谱干涉椭偏系统,搭建马赫曾德实验光路,实现了近红外波段硅基底上膜厚的测量,以100 nm厚度的二氧化硅薄膜为样品,实现了纳米级的测量精度。本文所提出的测量方法适用于透明或非透明基底的薄膜厚度测量,避免了检测过程的矫正步骤或光源更换,可应用于化学气相沉积、分子束外延等薄膜制备工艺和技术的成品的高精度检测。