欧姆接触电阻率的精确测量方法

分析了一般测量接触电阻率的TLM模型以及“端电阻”修正模型的缺点,提出了一种新的接触电阻率的测试方法。此方法模型精确,常规测试条件下容易得到误差小于1%的相关测试量的值,使接触电阻率的测试误差小于5%。     

斜置式方形探针测量单晶断面电阻率分布mapping技术

介绍了一种应用斜置式方形探针测量单晶断面电阻率的测试方法,将Rymaszewski直线探针测试方法引入到方形探针测试,并对测试过程中产生的游移以及图像监控问题进行了讨论.应用此测试方法得到了75mm的全片电阻率分布的mapping图,测试结果表明该方法可以在测量区域明显减小的同时保证测量的精确性,是一种行之有效的测量方法.     

非接触半绝缘SiC电阻率测试

半绝缘碳化硅单晶(SI-SiC)是非常具有吸引力的大功率电子器件衬底材料,目前已越来越多地引起了人们的重视。其晶片电阻率的测试一直是一个难题。介绍了一种非接触电阻率测试方法,可以有效地解决这一难题。该方法利用电容充放电原理。首先对样品进行瞬时充电,再利用仪器实时检测放电过程中的总电量,从而得到其变化的弛豫曲线,之后对该曲线进行数学分析得到弛豫时间τ,最后利用弛豫时间τ计算出半绝缘碳化硅单晶的电阻率。实际测试时,先将晶片表面划分为若干等面积的小区域,再利用仪器逐个测试这些区域的电阻率,最后将所有电阻率的数据处理成一张电阻率分布图。该方法对半绝缘材料的研究工作具有积极的指导作用。     

斜置式方形探针测量单晶断面电阻率分布mapping技术

介绍了一种应用斜置式方形探针测量单晶断面电阻率的测试方法 ,将Rymaszewski直线探针测试方法引入到方形探针测试 ,并对测试过程中产生的游移以及图像监控问题进行了讨论 .应用此测试方法得到了 75mm的全片电阻率分布的mapping图 ,测试结果表明该方法可以在测量区域明显减小的同时保证测量的精确性 ,是一种行之有效的测量方法     

激光高频法测量硅单晶少子寿命

本工作采用波长1.06微米的机械调Q激光器作光源,用高频光电导衰减法测试电阻率在1～10欧-厘米范围内的硅单晶少子寿命,获得了较好的初步成果。这种改进寿命测试方法的特点是激光技术和高频无接触耦合,故定名为“激光高频法”,该方法所需设备和测试操作都不太复杂,适当改进后,可作为一种测试大规模集成电路用的低阻硅材料少子寿命的常规方法。     

自对准栅金刚石MESFET器件研究

基于表面氢化处理的金刚石材料,利用自对准栅工艺技术研制了p型金刚石肖特基栅场效应晶体管(MESFET)。利用AFM和Raman测试方法对材料的特性进行了测试及分析。同时,对研制的金刚石MESFET器件进行了TLM以及直流特性测试及性能分析。利用TLM方法测试获得的表面氢化处理金刚石材料的方阻和Au欧姆接触比接触电阻率分别为4kΩ/□和5.24×10-4Ω.cm2。研制的1μm栅长金刚石MESFET器件的最大电流在-5V偏压下达到10mA/mm以上。     

P型GaN欧姆接触的比接触电阻率测量

采用多种传输线模型方法,测量了p型GaN上的欧姆接触的比接触电阻率.通过比较和分析不同测量方法所得的结果之间的差异,得出了一个准确、可靠测量p型GaN上的欧姆接触的比接触电阻率的方法--圆点传输线模型方法.利用该方法优化了p型GaN上欧姆接触的退火温度,在氧气气氛中650℃退火后获得了最优的欧姆接触,其比接触电阻率为5.12×10-4Ω·cm2.     

高频光电导衰减法测试Ge单晶少数载流子寿命

高频光电导衰减法是测量Ge单晶少数载流子寿命常用的方法,高频脉冲信号照射到单晶表面时,产生非平衡载流子,非平衡载流子的复合时间长短反映了少数载流子寿命的大小。电阻率越低,少数载流子寿命越小,仪器就难以测试。介绍了电阻率为0.03~0.04Ω.cm Ge单晶少数载流子寿命的测试方法。通过理论分析及实际测试,发现影响Ge单晶测试的主要因素有3个,即样品的表面状态、厚度及测试仪器的小注入水平。通过规范这些测试条件,能够测试低阻Ge单晶的少数载流子寿命。     

电阻率两种测试方法间几何效应修正的相关性

根据有限厚度样品体电阻率和薄层电阻两种测试方法间的厚度修正系数的相关性，论证了其边缘效应修正系数具有一一对应的严格的相等性。通过实验予以证明，并可将这一结论应用于非圆心点测试。     

用于紫外探测器的AlGaN/GaN异质结构的Ti/Al/Ni/Au欧姆接触特性

采用Ti/Al/Ni/Au多层金属体系在Al0.27Ga0.73N/GaN异质结构上制备了欧姆接触.分别采用线性传输线方法(LTLM)和圆形传输线方法(CTLM)对其电阻率进行了测试.当Ti(10nm)/Al(100nm)/Ni(40nm)/Au(100nm)金属体系在650℃高纯N2气氛中退火30s时,测量得到的最小比接触电阻率为1.46×10-5Ω·cm2.并制备了Al0.27Ga0.73N/GaN光导型紫外探测器,通过测试发现探测器的暗电流.电压曲线呈线性分布.实验结果表明在Al0.27 Ga0.73N/GaN异质结构上获得了好的欧姆接触,能够满足制备高性能AlGaN/GaN紫外探测器的要求.     

环保/水质测试仪器的进展

介绍了最常用的水质参数－－酸碱度，电导率／电阻率，溶介氧，固体悬浮物／浊度的测试和进展。     

Deposition and characterization of molybdenum thin films using dc-plasma magnetron sputtering

Molebdenum (Mo) thin films were deposited on well-cleaned soda-lime glass substrates using DC-plasma magnetron sputtering. In the design of experiment deposition was optimized for maximum beneficial characteristics by monitoring effect of process variables such as deposition power (100–200 W). Their electrical, structural and morphological properties were analyzed to study the effect of these variables. The electrical resistivity of Mo thin films could be reduced by increasing deposition power. Within the range of analyzed deposition power, Mo thin films showed a mono crystalline nature and the crystallites were found to have an orientation along [110] direction. The surface morphology of thin films showed that a highly dense micro structure has been obtained. The surface roughness of films increased with deposition power. The adhesion of Mo thin films could be improved by increasing the deposition power. Atomic force microscopy was used for the topographical study of the films and to determine the roughness of the films. X-ray diffractrometer and scanning electron microscopy analysis were used to investigate the crystallinity and surface morphology of the films. Hall effect measurement system was used to find resistivity, carrier mobility and carrier density of deposited films. The adhesion test was performed using scotch hatch tape adhesion test. Mo thin films prepared at deposition power of 200 W, substrate temperature of 23°C and Ar pressure of 0.0123 mbar exhibited a mono crystalline structure with an orientation along (110) direction, thickness of ～550 nm and electrical resistivity value of 0.57 × 10^?4 Ω cm.     

In-line monitoring of 300 mm silicon epitaxial and CZ wafers using surface charge profiler

The surface charge profiler (SCP) offering non-contact electrical characterization of the near-surface region of silicon wafers is discussed. The system permits fully automatic handling of 300- and 200-mm wafers. The SCP method, based on a low intensity illumination a.c. surface photo-voltage principle, does not require any surface preparation. It allows for a fast (600 points/min), high-resolution mapping of the active doping concentration in the near-surface region as well as surface recombination lifetime. The capabilities of the SCP method for process monitoring and development are illustrated with 200- and 300-mm wafers, focusing on the effects of epi growth conditions on the layer uniformity and its resistivity.     

Dynamic Imaging in Electrical Impedance Tomography of the Human Chest With Online Transition Matrix Identification

One of the electrical impedance tomography objectives is to estimate the electrical resistivity distribution in a domain based only on electrical potential measurements at its boundary generated by an imposed electrical current distribution into the boundary. One of the methods used in dynamic estimation is the Kalman filter. In biomedical applications, the random walk model is frequently used as evolution model and, under this conditions, poor tracking ability of the extended Kalman filter (EKF) is achieved. An analytically developed evolution model is not feasible at this moment. The paper investigates the identification of the evolution model in parallel to the EKF and updating the evolution model with certain periodicity. The evolution model transition matrix is identified using the history of the estimated resistivity distribution obtained by a sensitivity matrix based algorithm and a Newton–Raphson algorithm. To numerically identify the linear evolution model, the Ibrahim time-domain method is used. The investigation is performed by numerical simulations of a domain with time-varying resistivity and by experimental data collected from the boundary of a human chest during normal breathing. The obtained dynamic resistivity values lie within the expected values for the tissues of a human chest. The EKF results suggest that the tracking ability is significantly improved with this approach.      

Surface Resistivity Characterization of New Printed Circuit Board Materials for Use in Spacecraft Electronics

New dielectric materials have been introduced for printed circuit board applications, such as Thermount and polyimide with the aim to match the requirements for high speed and high density of electronic devices that are planned for new spacecraft electronic boards. Before these newer substrate can fully replace the well-known space-approved material epoxy FR-4, it is necessary to investigate more deeply their electrical and mechanical properties. The scope of this study is to report quantitative characterization of the surface resistivity for the different material samples under various testing conditions that include relative humidity, temperature, solder flux contamination, and corona discharge. The surface resistivity results are reported for sets of samples measured under a combination of testing conditions.     

电池片电参数测试机构的研究

太阳能电池片测试分选机用于太阳能单晶硅和多晶硅电池片的电性能测量与分选,通过模拟太阳光谱光源对电池片的相关电参数进行测量,依据测量的结果将电池片进行分档。在整个工艺流程中,测试部分是最为重要的环节,测试机构的精准度直接影响测量及分选的结果,基于此介绍太阳能电池片测试分选机测试机构的设计与测量原理。     

The Dependence on Thermal History of the Electrical Properties of an Epoxy-Based Isotropic Conductive Adhesive

The effect of thermal history on the electrical resistivity of a typical isotropic conductive adhesive (ICA) composed of an epoxy-based binder has been investigated in the present work. The electrical resistivities of test specimens were found to be different depending on the curing temperature, even if they exhibited similar degrees of conversion, although the values of T _g for the ICA specimens were determined by their degree of conversion, regardless of the curing temperature. Postannealing effects in terms of decreased electrical resistivity could be induced at a temperature in the vicinity of the glass transition temperature (T _g ), even if the specimens already achieved full conversion during the preliminary curing process. The magnitude of the annealing effect was found to depend on the preliminary curing and postannealing temperatures. When the specimens exhibit conversions of greater than 25% prior to the postannealing process, the preliminary curing state of the binder can influence the electrical resistivity of the ICA that is obtained after annealing.     

矿用无触点电气开关的研究

目前,我国煤井所采用的开关器件大多为交流接触器,动作时容易产生火花,瓦斯遇到电气火花具有爆炸的可能,会直接威胁到矿井和工人们的生命安全。为了解决这一问题,使用无触点电气开关取代有触点的各类接触器是避免电气火花的有力措施。     

泰克实时频谱仪在RFID测试中的应用(下)

RFID技术作为一种重要的非接触式识别技术,近来发展迅猛。在RFID测试中使用的传统测试仪器通常没有提供专用测试功能,泰克频谱分析仪追加了特殊测试功能。为了说明泰克频谱分析仪在RFID测试中的应用方法,本文介绍了RFID的相关知识以及在各频段中的不同应用,RFID相关设备和系统遵循的标准和法规,RFID的具体测试要求以及使用该仪器对RFID设备进行测试的有关内容。