On the data interpretation of the C-AFM measurements in the characterization of thin insulating layers

The interpretation of the conductive atomic force microscopy (C-AFM) results is discussed in the framework of the characterization of the high-k layers as gate oxide. Because the high-k layer is deposited on an interfacial layer, at high gate voltage, the C-AFM current maps do not reflect the high-k properties but rather the interface. Moreover, in the point contact mode, the surface of the equivalent capacitor as well as the voltage and current ranges used with the C-AFM are different from the one used in common IV. The interpretation of macroscopic measurements can therefore not be transposed to the C-AFM results. More specifically, the shift towards lower voltage of the backward curve is ascribed to the creation of a conducting path at high voltage.     

红外经纬仪视频图像判读系统研究

红外经纬仪在海上靶场测控中有重要作用,对红外视频图像的判读直接影响红外经纬仪的测角精度。通过对红外视频图像的判读原理和方法的介绍,针对靶场红外图像的特点,提出一种中轴线判读方法,以及基于最大类间方差法的高阈值图像二值化算法,提高了视频判读的稳定性和准确性。在此基础上研制了一套红外视频图像判读系统,试验结果和误差分析表明了所提方法的有效性。     

On the accuracy of a cellular location system based on RSS measurements

We discuss the performance of a cellular location system based on received signal strength (RSS) measurements. Each mobile station (MS) collects RSS measurements of the downlink control channels transmitted by the surrounding base stations. It is assumed that there is one-to-one mapping between the RSS and the MS location. Hence, these measurements can be used to obtain the MS location. We examine the accuracy of this method by deriving the Cramer-Rao bound, the concentration ellipse, and the circular error probability (CEP) of this method. In addition, we obtain an analytic expression that predicts the point at which accuracy deviates significantly from the bound (the threshold point). The accuracy of the method does not meet the FCC E911 requirement, but it is an attractive solution for less-demanding location-based services.     

New interpretation of spot-size measurements on singly clad single-mode fibres

By using the Petermann spot size rather than the Marcuse spot size we suggest a slight modification to the Millar method for ESI determination which will allow the three parameters necessary for the EESI to be determined. The method is particularly useful for triangular-profile fibres.     

A program to provide information on the accuracy of electrical measurements

This paper describes a program for disseminating state-of-the-art information concerning accuracies in certain electrical measurements. The program is to be carried out by IRE Subcommittee 25.1, Basic Standards and Calibration Methods, who will employ task groups made up of representatives from industrial, government, and educational institutions for assistance in assembling information and preparing reports. The initiation of the work has been approved by IRE Committee 25, Measurements and Instrumentation, and IRE Committee 20, Standards. A discussion is given of the needs, plans, procedures and benefits of the program. Since the entire electrical industry can benefit greatly by this effort, this paper is being published so that members of the IRE can become acquainted with it and submit constructive suggestions for the implementation and extension of the program.     

A new interpretation of "End" resistance measurements

We propose a new interpretation of the "end" resistance measurements for field-effect transistors (FET's). This interpretation is based on the solution of the current transport equations under the gate and relates the "end" resistance to the source series resistance and the channel resistance of the device. The values of the series source and drain resistances determined for GaAs ion-implanted FET's, using our formulas for the "end" resistance, are in excellent agreement with the values obtained using our modification of the Fukui method [1].     

Passive electrical measurements from three Oklahoma tornados

Passive electrical measurement of three tornados in the Oklahoma area have been made and are being reported upon. The measurements made include point discharge current, 18.5-kc/s sferics, along with 10-, 50-, 100-, and 175-kc/s, and 30-Mc/s sferics. The preceding measurements of tornados are compared with a typical local thunderstorm. In this comparison, it is shown that the electrical discharges within the tornados are much more intense than in local thunderstorms, particularly in frequency of occurrence. Data also show that the normal frequency spectrum of sferics radiation is different from the frequency spectrum of the tornados measured. Furthermore, the tornado sferics appear to have a definite aperiodic structure that may be present to a limited extent in the intense portion of a thunderstorm. Similarities between the measurements made on the Oklahoma tornados and Jones's work are pointed out. Finally, it is suggested that a coupling between the electrical and mechanical energies of the tornado may be responsible for the difference noted between tornado sferics and thunderstorm sferics.     

Use of short-loop electrical measurements for yield improvement

Modern submicron processes are more sensitive to both random and systematic wafer-level process variation than ever before. Given the dimensional control limitations of new technologies, the amount of wafer-to-wafer and within wafer nonuniformity of many steps is becoming a significant fraction of the total error budget, which already includes the usual step-to-step allocations. However, a significant portion of the total observed variability is systematic in nature. Accordingly, particle defects may not continue to dominate parametric yield loss without improved understanding of parametric variations. In this paper, we demonstrate the use of short-loop electrical metrology to carefully characterize and decouple wafer-level variability of several critical processing steps. More specifically, we present our method and give results obtained from variability analyses for lithography critical dimension (CD) and inter-level dielectric (ILD) thickness control. Using statistically designed experiments and dedicated test structures, the main factors affecting dielectric thickness variability has been identified. The systematic variability from a wafer stepper has been extracted using a physically based statistical data filter. Once isolated, the deterministic variability can be modeled and controlled to enhance process and circuit design for manufacturability (DFM). We hope that in the future this work will be coupled with novel DFM-oriented CAD tools that encapsulate this information in a fashion that makes it useful to process and circuit designers     

RF electrical measurements of fine pitch BGA packages

A series of fine pitched ball grid arrays (BGAs) were measured on an Network Analyzer using a novel technique to de-embed the package test fixture and provide an accurate representation of the electrical characteristics of the package. The technique consisted of the design and fabrication of a RF circuit board. Duplicates of the board were modified to become a series of calibration fixtures while others, with sample packages attached, were modified to become test fixtures. The packages, attached to circuit boards, were measured to determine their performance at the RF frequencies of most cellular phone applications. Measurements included the return losses looking into several leads of the package that were 50 Ω terminated and insertion losses from one terminated lead to an adjacent one. These measurements can be used for verifying models or for characterizing packages     

Determination of electrical and mechanical parameters in capacitive MEMS accelerometers using electrical measurements

This paper describes a simple technique for characterization of capacitive MEMS accelerometers. The method is based on electrical impedance (admittance) measurements of capacitive MEMS accelerometers treated as electrostatically-driven microelectromechanical resonators. By using this method, it is possible to determine some electrical and mechanical parameters including the shunt capacitance, the mechanical resonance frequency and quality factor. These parameters may serve as measures of structural integrity of the tested structures and their packages during reliability testing, for instance.     

浅谈发电厂的电气综合自动化系统

发电厂作为能源转换电能的工厂,随着我国科学技术不断的发展,发电也有效的利用了电气自动化技术,使其电气综合自动化系统,在满足人们用电需求的同时,降低了经营的成本,从而有效的促进我国经济的发展。对此本文就发电厂的电气综合自动化系统,结合其定义、发展以及功能改造进行分析,并提出相关的见解,希望对于我国电力系统的完善,有着积极促进的意义。     

Satellite system measurements

This paper describes the measurement techniques employed to test the elements of a communications satellite system. Techniques for measuring the gain-to-noise-temperature ratio (G/T) of an earth station antenna are presented. The measurement of earth station polarization characteristics is discussed extensively in terms of the new requirement for frequency reuse on orthogonal polarizations. Methods for in-orbit measurement of spacecraft performance including antenna characteristics are included, as well as some typical experimental results.     

嵌入式电阻抗测量系统研究

为提高阻抗测量的便捷性及数字化应用,基于ARM架构的S3C2440处理器和Linux3.0.4内核,研发了一套嵌入式电阻抗测量系统。系统采用AD5933作为阻抗传感器,利用I2C通信协议实现AD5933与S3C2440处理器之间的数据通讯,开发QT用户界面实现测量结果的显示,通过操作触摸屏实现阻抗参数的采集、显示、保存及曲线绘制等功能。实验结果表明图像重建质量较好,信噪比达65.6dB,验证了系统软硬件设计的可靠性与稳定性。该研究有助于推动阻抗测量技术在数字化医疗及临床应用的发展。     

Trace copper measurements and electrical effects in LPE HgCdTe

Recent improvements in sputter initiated resonance ionization spectroscopy (SIRIS) have now made it possible to measure copper in HgCdTe films into the low 10¹³ cm⁻³ range. We have used this technique to show that copper is responsible for type conversion in n-type HgCdTe films. Good n-type LPE films were found to have less than 1 x 10¹⁴ cm⁻³ copper, while converted p-type samples were found to have copper concentrations approximately equal to the hole concentrations. Some compensated n-type samples with low mobilities have copper concentrations too low to account for the amount of compensation and the presence of a deep acceptor level is suggested. In order to study diffusion of copper from substrates into LPE layers, a CdTe boule was grown intentionally spiked with copper at approximately 3 x 10¹⁶ cm⁻³. Annealing HgCdTe films at 360°C was found to greatly increase the amount of copper that diffuses out of the substrates and a substrate screening technique was developed based on this phenomenon. SIRIS depth profiles showed much greater copper in HgCdTe films than in the substrates, indicating that copper is preferentially attracted to HgCdTe over Cd(Zn)Te. SIRIS spatial mapping showed that copper is concentrated in substrate tellurium inclusions 5–25 times greater than in the surrounding CdZnTe matrix.     

On the interpretation for radiation from simple currentdistributions

We have considered the radiation from two simple filamentary current distributions: traveling-wave and uniform. For an excitation that is a Gaussian pulse of characteristic time τ, the total energy radiated by the distributions, U_rad, was shown to behave as ln(τ_a/τ) for the traveling-wave distribution, and as τ_a/τ for the uniform distribution, where τ_a =h/c is the time for light to travel the length of the filament. An examination of numerical results shows that two physical interpretations can be used for the radiation. Radiation can be considered to arise at the two ends of the filament in the form of spherical wavefronts centered at the ends. The overlap of these wavefronts, which changes with the ratio τ_a/τ, is the cause of the observed dependencies for U_rad. An alternative explanation is that radiation occurs along the entire length of the filament. Destructive interference of the radiation from different points on the filament then causes the radiation to be insignificant except at the times corresponding to radiation from the ends of the filament     

On the interpretation for radiation from simple currentdistributions

It is indisputable that Maxwell's equations provide a unique electromagnetic field for any reasonable distribution of charge/current. However, the interpretation of the results from such calculations may not be unique; different physical models may be used to explain the same results. We examine the radiation from similar filamentary current distributions (traveling-wave and uniform) for pulse excitation. For pulse excitation, it is easier to establish the causal relationship between the elements of current and the radiated field. We also show, for these simple distributions, that the total energy radiated for pulse excitation depends on the length of the filament in the same way as for the time-harmonic case     

航空电气系统绝缘电阻自动测试系统研究

为了提高航空的安全性,降低发生故障的概率,很多部门开始深入研究航空电气系统绝缘电阻自动测试系统,进一步提高测试的准确度,降低测试成本,提高企业的经济效益.     

电气自动化控制系统的应用安全性研究

电气设备的自动化控制是现阶段电气发展的重要内容,通过自动化的控制方式可以解决以往人工控制所面临的诸多问题,提升控制效率和准确度。文章对目前的电子自动化控制系统进行了研究,全面分析了电子自动化控制系统的使用现状,并从中总结出了影响自动化系统应用安全的几个方面原因,最后结合自动化技术的研究,提出了提升自动化控制系统使用安全性的建议。