MCZ硅单晶反型杂质含量研究

利用范德堡－霍尔测量方法对ＭＣＺ硅单晶的反型杂质含量进行了对比测量，所得结果表明，ＭＣＺ硅单晶的反型杂质含量低于ＣＺ硅单晶约半个数量级之多，文中还提出了一种适合于大指范德堡－霍尔测量的接触电极制备方法－选择扩散法，并给出了确保测量方法带来影响的扩散结深与样品厚度比值上限ｘｊ／ｄ＝０．０１。测量过程中应用了有限尺寸接触电极修正理论。     

基于里德堡原子的微波相移测量

基于里德堡原子的微波量子精密测量技术由于其高灵敏度、高分辨、宽带宽且可直接溯源至基本物理常数等优势，已在微波量子计量、通信、成像等领域展现出广阔的应用前景。通过提出一种基于里德堡原子的微波相移测量方法，利用热里德堡原子光谱实现对本振(LO)微波场与待测(SIG)微波场的外差探测，得到了相移与待测微波场相移相同的中频(IF)探测信号；然后利用锁相放大算法对探测信号进行处理，得到探测信号相对同频参考信号的相位差；最后，利用位移台在待测微波信号中引入相移，比较位移前后的相位差测量结果，实现了6.92 GHz微波信号相移的测量。对相移测量结果进行线性拟合，得到该频率的微波传播常数，与理论计算结果的相对误差约为0.2%,验证了这种全光学微波相移测量方法的可行性，并为微波量子精密测量技术在通信雷达等领域的应用奠定了基础。     

QPSK调制多载波信号时延在线测量技术

针对传统通用仪器无法完成对新一代扩频测控系统QPSK调制多载波信号时延在线测量的难题,通过对基于QPSK调制的多载波信号进行深入研究,提出了此类信号时延测量方法:利用光纤传输实现了同步信号上升沿低失真远距离传输;利用FIR数字滤波实现了无非线性失真、滤波时延可计算的多载波分离;利用结合时间窗的解包络技术实现了QPSK调制信号的时延测量。并基于上述测量方法提出了测量系统构架,研制了QPSK调制多载波信号时延测量系统,完成了对转发式卫星导航试验系统射频信道上行链路时延在线高精度测量。     

Hg1-xMnxTe晶片电学参数的测量及分析

采用范德堡法分别在77K和室温下对多个Hg1-xMnxTe晶片的电学性能进行了测量,发现部分晶片在77K下的导电类型为p型,而在室温下却为n型.通过理论分析对此现象进行了解释.分析表明:Hg1-xMnxTe晶片中电子迁移率与空穴迁移率的比值较大和Hg1-xMnxTe的禁带较窄是造成晶片导电类型转变的主要原因.对所测其它电学参数的理论分析表明范德堡法不适合用于Hg1-xMnxTe晶片室温时的载流子浓度和迁移率的测量,但仍可用其对晶片室温时的电阻率和霍尔系数进行测量.     

微弱信号测量的一种实现方法

介绍了一种μＶ级微弱电信号测量的实现方法,给出了测量放大电路的具体设计以及信号采集与处理软件流程图。与传统测量方法相比,此测量方法所使用的仪器体积小,重构测量系统方便,可直接由计算机对信号进行分析,是目前信号测量的主要发展方向。     

ADS注入器Ⅰ真空测量与控制系统研制

本文完成了ADS注入器Ⅰ真空测量系统及其相关设备控制系统的设计,详细阐述了测量方法、控制逻辑、设备组成及通讯协议,分析了PLC阀门控制器工作模式及控制流程。测量和采集真空系统的实时状态,包括皮拉尼、冷规信号的采集和冷规电节点0/1信号采集,分子泵和离子泵等的状态信号。通过分析系统实际运行情况,发现强电磁场对于真空冷规的测量有较大的干扰。因此,对于需要与冷规信号一起联锁控制的真空系统,需考虑该干扰造成的影响。本文采用的相邻两个冷规信号联锁的方案,在一定程度上可避免强电磁场带来的信号干扰引起的系统保护。     

一种基于高频脉冲插值的角加速度测量系统

设计了一种角加速度测量系统.测量方法是通过高精度光栅和红外光电管获取转速信号,再对转速信号进行高频脉冲插值,从而把转速信号转化为高频脉冲数,对高频脉冲数处理后得到转轴的角加速度.测量系统采用FPGA与单片机相结合的模式,FPGA用于产生高频脉冲、对转速信号插值,并对插值后的信号进行计数,单片机读取计数结果并进行处理.实验验证表明,该角加速度测量系统有较高的测量精度.并通过理论分析找到了影响系统测量精度的原因.     

转动惯量测量系统的研制

介绍了一种新的利用三线摆测量转动惯量的系统及方法,该方法采用传感器和数据采集装置采集计算转动惯量所需的周期信号和力信号;并通过开发出专门的软件,最终计算出待测物体的转动惯量。该方法将机械装置与电子部件和计算机相结合,与原有的传统测量方法相比,避免了手动操作和人工计算,方便实用,能够对大型刚体进行测量;整个过程趋于自动化,提高了测量精度和效率。     

硝酸铵水溶液浓度快速检测方法

为实现含水硝酸铵炸药水相配料溶液浓度的在线实时测量,通过测量已知浓度的硝酸铵水溶液在不同温度下的电导率,做出硝酸铵水溶液的温度-电导率-浓度的标准曲线。测量被测硝酸铵水溶液的电导率和温度,与上述标准曲线比较,从而求得被测硝酸铵水溶液的浓度。将标准曲线数据导入作为生产在线监控系统,并且将被测硝酸铵水溶液的电导率和温度的测量信号通过传输线路与计算机相连,则可实现硝酸铵水溶液浓度的在线快速检测。     

四电极法电导率仪电计检测技术的探讨

四电极法测量电导率技术近几年发展迅速,国内用户使用的四电极法电导率仪主要有美国ORION公司、意大利HANNA公司、瑞士Mettler-Toledo公司。目前国内没有一家公司应用此技术开发商品电导率仪,因此,加强这方面的技术研究,促进我国检测技术的早日普及非常必要。一、四电极法测量基本原理电导率的传统测量方法是采用两电极技术,测量原理如图1所示,电导率的测量过程中,两电极间加上恒定振幅的电压信号,电极上流经一定的电流Ix,电流大小取决于溶液中所含离子的数量,被测介质的电导率与运算放大器的输出电压成正比。这种两电极技术测量过程…     

半导体电学特性四探针测试技术的研究现状

四探针法是材料学及半导体行业电学表征较常用的方法,其原理简单,能消除接触电阻影响,具有较高的测试精度.由厚块原理和薄层原理推导出计算公式,并经厚度、边缘效应和测试温度的修正即可得到精确测量值.据测试结构不同,四探针法可分为直线形、方形、范德堡和改进四探针法,其中直线四探针法最为常用,方形四探针多用于微区电阻测量.本文综述了四探针测试技术的基本理论,包括四探针法的分类、原理和修正,并阐述了四探针测试技术在微观领域的发展.     

高技术功能薄膜材料电阻率测试新法及微机测试系统

介绍一种适于测量几何形状无规则的薄形样品电阻率的改进直流四探针法(IFPM),同时提出了带背底样品的测试实验修正原理和方法。采用具有标准IEEE—488接口和24路I/0控制接口的PC/XT微机和智能数字仪表组成测试实施系统,在Solartron35 system上用范德堡法(VDPM)和在本系统上用IFPM法对同一块硅单晶片进行了对比测试,二者偏差为4.3％。采用该法还测试研究了直流电弧等离子体喷射技术在陶瓷基底上制备的1μm厚铜-聚丙炔腈(Cu-PPN)金属有机导电薄膜的电阻率与温度的关系,结果表明Cu-PPN薄膜具有非晶半导体的扩展传导机制。研究表明,IFPM法对目前不能沿用传统技术的高技术薄膜材料电阻率测试是一条有效的途径。     

Galvanic deposition of nanocrystalline ZnO thin films from a ZnO-Zn(OH)(2) mixed phase precursor on p-Si substrate

A galvanic technique for the deposition of ZnO thin films is reported. The depositions were carried out on p-type single-crystal silicon substrates at room temperature, from a solution of ZnSO(4), where the Zn rod acted as a sacrificing anode and p-Si was the cathode. The deposition of ZnO by this method is pH sensitive, and a pH between 4 and 5 is found to be optimum for film deposition. This deposition technique is simple, inexpensive and can be carried out at room temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies revealed the nanocrystalline structure of the films. The resistivity of the annealed ZnO films was determined by the Van der Pauw measurement technique.     

共压共烧法制备La0.8Sr0.2(Ga0.8Mg0.2)0.1Fe0.9O3-δ致密扩散障碍层极限电流型氧传感器

采用固相合成法制备了La_0.8Sr_0.2(Ga_0.8Mg_0.2)_0.1Fe_0.9O_3-δ(LSGMF)混合导体和La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ(LSGM)固体电解质, 利用XRD、TGA、范德堡直流四探针法和热膨胀仪等对试样进行了分析。以LSGMF为致密扩散障碍层, 以LSGM为氧泵层, 采用共压共烧结法制备了极限电流型氧传感器, 利用SEM和EDS对LSGMF/LSGM陶瓷体横截面的微观形貌和成分进行了分析。结果表明: LSGMF具有菱方钙钛矿结构(R-3c空间群), 它在650℃失重速率最快, 其电导率随温度的升高而增大; 300~1000℃范围, LSGM与LSGMF的热膨胀系数分别为12.51×10^-6/℃和12.80×10^-6/℃。650~850℃范围, 氧传感器具有良好的极限电流平台, lgI_L(极限电流I_L)与1000/T呈线性关系, LSGMF中氧离子的扩散激活能为0.4008 eV。800℃、0.3mol%<x(O₂)<21.0mol%时, 极限电流I_L与氧含量x(O₂)间的关系为: I_L(mA)=10.285x(O₂)(mol%), R=0.9982。LSGMF和LSGM结合牢固, 未产生裂纹, EDS分析基本符合各化合物的化学计量比。     

Structural,mechanical, and electrical properties of carbon nanoparticles synthesized from diesel

We studied the elemental analysis, structural morphology, mechanical, and electrical properties of carbon nanoparticles synthesized from diesel. The spherical carbon particle size in the range of about 10 to 80 nm in diameter was observed in scanning electron microscope (SEM) studies that were identified by Atomic force microscopy (AFM) study as an aggregation of carbon particles of average size 2.5 nm. The surface rms of carbon nanoparticle thin film (CNTF) was measured directly by AFM and found 0.22 nm. The Derjaguin–Muller–Toporov (DMT) elastic modulus of carbon nanoparticles (CNPs) was measured by PeakForce QNM mode of AFM. The minimum and maximum elastic modulus was measured of 0.40 GPa and 43.89 GPa, respectively. The resistivity, conductivity, magneto resistance, mobility, and average Hall co-efficient were measured by “Ecopia Hall-effect measurement system” by four-point Van der Pauw approach at ambient condition. We demonstrated I–V characteristic at the Indium/CNTF thin film interface, which is accompanied by rectifying behavior.     

Evidence of p-doping in ZnO films deposited on GaAs

Successful p-type ZnO thin films have been reported by depositing it on semi insulating GaAs substrates by Pulsed Laser Deposition (PLD) technique. The PLD samples were subsequently subjected to Rapid Thermal Annealing to achieve the required doped ZnO. X-ray Diffraction, Atomic Force Microscopy and Van der Pauw Hall measurements were performed on the annealed samples and compared with as-deposited ones. The XRD results confirm growth of <002> ZnO along with better crystallinity for the annealed sample. The AFM results reveal that the thin films deposited were highly uniform having very low roughness values. Van der Pauw Hall measurements show a transition from n-type conductivity for as-deposited sample to p-type for annealed samples. The hole concentration and Hall mobility measured were reported to be as high as 4.475 × 10²⁰ cm^− 3 and 39.73 cm²/V-sec respectively. These are probably the highest reported values to date and are encouraging from the point of successful fabrication of efficient ZnO-based optoelectronics devices like LED, laser, photodiodes, etc. in the near future.     

Optical and electrical properties of fluorine doped tin oxide thin film

Thin film of SnO₂:F was prepared by spray pyrolysis technique on glass substrate. Surface Morphology, using scanning electron microscope, shows micrograph image with grains size distribution between 16 and 380 nm. Structural characterization by XRD indicates a similar rutile polycrystalline material as SnO₂. A four point probe I–V measurement (Van der Pauw method) was used to study electrical properties and the result shows a room temperature sheet resistance of 24 Ω/sq. In addition, a temperature dependence of the electrical response indicates that defect scattering is the main contribution to the DC resistivity. Optical properties were studied by UV–Visible spectroscopy and the spectrum was fitted using Drude-Lorentz model with DC conductivity value (frequency equal to zero) as a fitting condition. Optical result shows average transmittance around 81.2% for the visible frequency range. It indicates a TCO figure of merit value of 5.2?×?10^?3 Ω^?1. In addition, a first principle calculation using DFT with PBE0 hybrid exchange-correlation was realized to SnO₂ and SnO₂:F systems in order to understand, from a theoretical point of view, the experimental results. Finally, the FTO film was utilized and evaluated as a transparent electrode in the preparation of a dye-sensitized solar cell.     

Conductivity for soot sensing: possibilities and limitations

In this study we summarize the possibilities and limitations of a conductometric measurement principle for soot sensing. The electrical conductivity of different carbon blacks (FW 200, lamp black 101, Printex 30, Printex U, Printex XE2, special black 4, and special black 6), spark discharge soot (GfG), and graphite powder was measured by a van der Pauw arrangement. Additionally the influence of inorganic admixtures on the conductivity of carbonaceous materials was proven to follow the percolation theory. Structural and oxidation characteristics obtained with Raman microspectroscopy and temperature programmed oxidation, respectively, were correlated with the electrical conductivity data. Moreover, a thermophoretic precipitator has been applied to deposit soot particles from the exhaust stream between interdigital electrodes. This combines a controlled and size independent particle collection method with the conductivity measurement principle. A test vehicle was equipped with the AVL Micro Soot Sensor (photoacoustic soot sensor) to prove the conductometric sensor principle with an independent and reliable technique. Our results demonstrate promising potential of the conductometric sensor for on-board particle diagnostic. Furthermore this sensor can be applied as a simple, rapid, and cheap analytical tool for characterization of soot structure.