MIS characterization and modeling of the electrical properties of the epitaxial Caf2/Si(111) interface

CaF₂ layers have grown by molecular beam epitaxy on bothn-type andp- type Si(111). Capacitance-voltage (C-V) and current-voltage (I-V) measurements have been made on metal-insulator-semiconductor (MIS) capacitors to characterize these structures. For devices onp-type Si, C-V characteristics show only the insulator value of the capacitance over a wide range of applied voltages, indicating an accumulated surface. At room temperature, C-V characteristics ofn-type devices show the minimum value of the capacitance (corresponding to inversion) for small voltages, but modulation of the capacitance at larger voltages. At 200 K, this modulation is no longer present in the C-V curves. I-V curves show a rapid increase in the leakage current at relatively low fields at room temperature, and this leakage decreases dramatically with temperature. These results are largely independent of cleaning procedure, growth temperature, and the degree of misalignment of the substrate. The characteristics are modeled by assuming the Fermi level to be pinned at the valence-band edge, and the modulation in the C-V characteristics ofn-type samples to be driven by leakage currents. Work done at GE while a graduate student in the School of Electrical Engineering, Cornell University. Present address: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109.     

85℃3000小时系列焊片式铝电解电容器的开发研究

该次试验的目的是为了开发出85℃3000小时这种新的系列的焊片式铝电解电容器。为此，对该系列选取了最小电压200V的小容量和大容量，及最大电压450V的小容量和大容量的产品分别进行了设计和开发。开发过程中对阳极箔，阴极箔，电解纸，电解液等原材料进行了分析比较，并将四种设计分别做成产品并测试最薄弱的环节85℃3000小时的纹波电流试验，结果表明该系列的设计能很好地满足电性能要求。     

Wideband LC balun transformer using coupled LC resonators embedded into organic substrate

In this paper, wideband LC balun using coupled LC resonator has been newly designed, simulated, and fabricated. The proposed balun has a novel scheme which consists of two pairs of coupled embedded LC resonators which share one resonator with each other. The coupled resonators are applied to provide a precise phase difference of 180° and an identical magnitude between two balanced ports and DC isolation characteristic with impedance transformation. Furthermore, proposed resonators have relatively small inductance values which can be easily embedded into the organic package substrate. In order to reduce the size of embedded capacitors, BTO composite high dielectric film was applied to increase their capacitance densities. The measured results of fabricated wideband balun exhibited an insertion loss of 1.8 dB, a return loss of 10 dB, a phase imbalance of 0.5°, and magnitude imbalance of 0.7 dB at frequency bandwidth of 700 MHz ranged from 1.8 to 2.5 GHz, respectively. They agreed well with the simulated ones. The fabricated balun has a relatively small volume of 2 mm×3.5 mm×0.66 mm (height).     

关于电容器及电容教学思考

电容器及电容是"工程电磁场原理"学习静电场和恒定电场时遇到的一个知识点,教材通常先给出电容器的定义,然后直接给出电容表达式,没有推算过程及对结果的分析.本文通过场分布推导电容表达式,并举例对结果进行讨论,实践证明教学效果有所改善.     

Li-defect interactions in electron-irradiated n-type silicon by EPR measurements

Single crystal silicon, both with and without oxygen, has been diffused with lithium to concentrations ～10¹⁷/cm², irradiated with 1 to 1.5 MeV electrons, and the ensuing defects studies by EPR measurements. The presence of oxygen strongly affects the properties of these defects. Measurements have indicated the presence of two new defects which involve Li-one in O-containing material and one in O-free material. The defects are observed in their electron-filled state, and indicate a net electron spinof ½. The defect spectra disappear (with time) at room temperature, and can be explained by the formation of other Li-involved defects which lie deeper in the energy bandgap and are not visible by EPR. Electron irradiation at 40 °K followed by annealing at higher temperatures show that both EPR defects described above begin to form at about 200 °K and begin to decrease at about 275 °K-just as does the 250 °K reverse annealing observed generally for n-type Si. Based on these data, and the work of others, it is suggested that both defects form as a result of the motion of Si interstitials which produce a (Li-O-interstitial) complex in O-containing Si, and a (Li-interstitial) complex in O-free Si.     

Thin ferroelectric poly(vinylidene fluoride-chlorotrifluoro ethylene) films for thermal history independent non-volatile polymer memory

In this study, we investigated the molecular and microstructures of thin poly(vinylidene fluoride-chlorotrifluoro ethylene) (PVDF-CTFE) copolymer films with three different CTFE compositions of 10, 15, 20 wt% with respect to PVDF in relation with their ferroelectric properties. All PVDF-CTFE annealed at 130 °C showed consecutive TTTT trans conformation with β type crystals while films molten and re-crystallized from a temperature above their melting points exhibited α type crystals with characteristic TGTG conformation. Microstructures of the films treated with the two different thermal histories also supported the formation of β and α type crystals with hundreds of nanometer scale sphere caps and micron level spherulites, respectively. Interestingly, PVDF-CTFE films with both α and β type crystals gave rise to relatively high remnant polarization of approximately 4 μC/cm² in metal/ferroelectric/metal capacitors regardless of the composition of CTFE. The ferroelectric polarization of a PVDF-CTFE film independent of thermal processing history allowed a wide processing window and easy fabrication protocol, resulting in a non-volatile ferroelectric field effect transistor memory which exhibited saturated hysteresis loops with the current ON/OFF ratio of approximately 10³ at ±60 V sweep and reliable data retention.     

Power dissipation characteristics of great power and super high speed semiconductor switch

The power dissipation characteristics of pulsed power switch reversely switched dynistors （RSDs） are investigated in this paper. According to the expressions of voltage on RSD, derived from the plasma bipolar drift model and the RLC circuit equations of RSD main loop, the simulation waveforms of current and voltage on RSD are acquired through iterative calculation by using the fourth order Runge-Kutta method, then the curve of transient power on RSD versus time is obtained. The result shows that the total dissipation on RSD is trivial compared with the pulse discharge energy and the commutation dissipation can be nearly ignored compared with the quasi-static dissipation. These characteristics can make the repetitive frequency of RSD increase largely. The experimental results prove the validity of simulation calculations. The influence factors on power dissipation are discussed. The power dissipation increases with the increase of the peak current and the n-base width and with the decrease of n-base doping concentration. In order to keep a low power dissipation, it is suggested that the n-base width should be smaller than 320μm when doping concentration is 1.0×10^14cm^-3 while the doping concentration should be higher than 5.8×10^13cm^-3 when n-base width is 270μm.     

CL81型高压聚酯膜电容器的阻燃试验

介绍了ＣＬ８１型高压聚酯膜电容器行业标准中关于阻燃试验的技术要求和试验方法。     

高纯铝箔再结晶晶粒度对比容的影响

通过对ＬＧ５－Ｙ、ＬＧ４－Ｙ两种国产箔退火工艺的研究，重点分析了铝箔再结晶晶粒度对比容的影响，并确定了高比容下的晶粒大小范围。从而为铝箔的退火工艺参数的确定提供了又一重要依据。     

A Novel Switched Parasitic Array and Diversity Scheme Using Horizontally Polarized Linear Antennas

Switched Parasitic Arrays (SPAs) are proposed as an attractive alternative to fully adaptive arrays, due to their compact size and significantly lower cost of development. The main concept of SPAs is the deployment of switches on parasitic elements, which can be properly adjusted, in order to effectively control the radiation pattern of one active element. Conventional SPAs consist of circular arrays of vertically polarized dipoles and parasitic elements. In this paper, a novel SPA design is proposed, which is based on multiple switches employed on the body of horizontally polarized elements (one active and two parasitics). Design considerations are discussed and numerical results are illustrated. Furthermore, a simple diversity scheme is proposed, based on the novel SPA design. Superior performance of the proposed array, relative to simple non-diversity reception schemes, is indicated by simulation results. Stelios A. Mitilineos was born in Athens, Greece, in 1977. He received the Diploma in electrical and computer engineering from the National Technical University of Athens (NTUA), Greece, in October 2001. He is currently working towards his Ph.D. degree in electrical engineering at the same university. His research interests include antennas and propagation, smart antennas and mobile communications, channel estimation and location detection algorithms, MIMO systems and microwave components. Anna E. Andreoudi was born in Thessalonica, Greece, in 1977. She received the Diploma in electrical and computer engineering from the National Technical University of Athens, in 2004. Her research interests include electromagnetic waves propagation and scattering, antenna design and adaptive arrays, wireless communications and wireless mobile networks. Christos N. Capsalis was born in Nafplion, Greece in 1956. He received the Diploma in electrical and mechanical engineering from the National Technical University of Athens in 1979 and the B.S. degree in economics from the University of Athens in 1983. He obtained the Ph.D. degree in electrical engineering from NTUA in 1985. He is currently a Professor at the department of Electrical and Computer Engineering in NTUA. His current scientific activity concerns satellite and mobile communications, antenna theory and design, and electromagnetic compatibility.