New SOI power device with multi-region high-concentration fixed interface charge and the model of breakdown voltage

A new SOI power device with multi-region high-concentration fixed charge(MHFC) is reported. The MHFC is formed through implanting Cs or I ion into the buried oxide layer(BOX), by which the high-concentration dynamic electrons and holes are induced at the top and bottom interfaces of BOX. The inversion holes can enhance the vertical electric field and raise the breakdown voltage since the drain bias is mainly generated from the BOX. A model of breakdown voltage is developed, from which the optimal spacing has also been obtained. The numerical results indicate that the breakdown voltage of device proposed is increased by 287% in comparison to that of conventional LDMOS.     

电荷耦合效应对高耐压沟槽栅极超势垒整流器击穿电压的影响

通过沟槽结构和可调节的电子势垒,沟槽栅极超势垒整流器可以更为有效地实现通态压降和反向漏电流之间的良好折衷.在高压应用时,电荷耦合效应对于提高该器件的反向承压能力起到了关键作用.本文通过理论模型与器件模拟结果,分析了沟槽深度、栅氧厚度和台面宽度等关键参数对电荷耦合作用下二维电场分布的影响,归纳出了提高该器件击穿电压的思路与方法,为器件设计提供了有意义的指导.在此基础上,提出了阶梯栅氧结构,该结构在维持几乎相同击穿电压的同时,使正向导通压降降低51.49%.     

Analysis of electrical tree propagation in XLPE power cable insulation

Electrical treeing is one of the major breakdown mechanisms for solid dielectrics subjected to high electrical stress. In this paper, the characteristics of electrical tree growth in XLPE samples have been investigated. XLPE samples are obtained from a commercial XLPE power cable, in which electrical trees have been grown from pin to plane in the frequency range of 4000-10,000 Hz, voltage range of 4-10 kV, and the distances between electrodes of 1 and 2 mm. Images of trees and their growing processes were taken by a CCD camera. The fractal dimensions of electric trees were obtained by using a simple box-counting technique. The results show that the tree growth rate and fractal dimension was bigger when the frequency or voltage was higher, or the distance between electrodes was smaller. Contrary to our expectation, it has been found that when the distance between electrodes changed from 1 to 2 mm, the required voltage of the similar electrical trees decreased only 1or 2 kV. In order to evaluate the difficulties of electrical tree propagation in different conditions, a simple energy threshold analysis method has been proposed. The threshold energy, which presents the minimum energy that a charge carrier in the well at the top of the tree should have to make the tree grow, has been computed considering the length of electrical tree, the fractal dimension, and the growth time. The computed results indicate that when one of the three parameters of voltage, frequency, and local electric field increase, the trends of energy threshold can be split into 3 regions.     

Influence of voltage pulse shape on the delay time for vacuum breakdown

In this paper expressions are derived for the delay time of vacuum breakdown with voltage pulses of ramp and trapezoidal shape. It is shown that the voltage pulse shape has a considerable influence on the delay time. The results obtained may be useful in experimental investigations of vacuum breakdown.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 105–110, September, 1976.     

脉冲电压下的自击穿水介质开关击穿特性和电路参数实验研究

 介绍了“强光一号”加速器中两种结构的自击穿水开关,建立了简化的开关电路模型,并通过估算和Pspice模拟确定了开关的电路参数,包括电极间杂散电容、火花通道电感和火花电阻。研究表明开关导通过程中的流注电容效应可以忽略,放电通道火花电感与电阻选取流注导通时刻的值,且在主放电电流传递过程中保持不变。根据实验结果,阐述了两种开关击穿的不同特点：对于局部电场增强型的球-板电极结构的主开关,可以采用J. C. Martin稍不均匀场水击穿经验公式估算临界场强;而棒-板电极结构的多针开关,适合用J. C. Martin针-板击穿模型的水击穿经验公式估算临界场强,且并联工作的9个多针开关可以同时形成独立的放电通道。     

空间电荷效应对阴极微凸起热不稳定性的影响

 由于金属微凸起爆炸电子发射的预发射电流密度一般都超过108 A/cm2,因此必须考虑其空间电荷效应的影响。基于金属微凸起爆炸电子发射起始过程模型,通过理论分析和数值模拟,给出了考虑预发射电流空间电荷效应的微凸起爆炸发射延迟时间随二极管平均电场的变化关系。与不考虑预发射电流空间电荷效应的结果进行对比表明,预发射电流的空间电荷效应可以显著增加金属微凸起的爆炸发射延迟时间。     

Influence of sub-bandgap illumination on space charge distribution in CdZnTe detector

The space charge accumulation in CdZnTe crystals seriously affects the performance of high-flux pulse detectors.The influence of sub-bandgap illumination on the space charge distribution and device performance in CdZnTe crystals were studied theoretically by Silvaco TCAD software simulation.The sub-bandgap illumination with a wavelength of 890 nm and intensity of 8×10?8 W/cm2 were used in the simulation to explore the space charge distribution and internal electric field distribution in CdZnTe crystals.The simulation results show that the deep level occupation faction is manipulated by the sub-bandgap illumination,thus space charge concentration can be reduced under the bias voltage of 500 V.A flat electric field distribution is obtained,which significantly improves the charge collection efficiency of the CdZnTe detector.Meanwhile,premised on the high resistivity of CdZnTe crystal,the space charge concentration in the crystal can be further reduced with the wavelength of 850 nm and intensity of 1×10?7 W/cm2 illumination.The electric field distribution is flatter and the carrier collection efficiency of the device can be improved more effectively.     

加压去离子水短脉冲击穿特性的初步研究

 液体的介质气泡击穿理论作为研究基础,开展了两种短脉冲下高压强水介质开关的击穿实验,获得了水介质击穿场强及耐压时间与水中压强关系的数据,通过分析比较得出：在脉宽300 ns和1 μs两种脉冲电压作用下,当水中压强逐渐提高时水介质击穿电压和耐压时间均呈上升趋势,压强越高趋势越明显,而且作用脉冲越宽水中压强对于水介质击穿特性的影响越显著。     

35kV低温绝缘超导电缆绝缘设计研究

主要研究了35k V低温绝缘超导电缆的绝缘特性。首先对低温绝缘材料聚丙烯层压纸PPLP(Polypropylene laminated paper)的绝缘性能进行了绝缘击穿试验研究,得到PPLP工频耐压及雷电冲击耐压的绝缘强度。在此基础上,设计了35k V低温绝缘超导电缆的绝缘,并且制作了模型样品,并对样品绝缘性能进行了局部放电试验及工频耐压试验,验证了设计的绝缘满足国家规定的电缆要求。对超导电缆的实际应用有着重要意义。     

One-dimensional breakdown voltage model of SOI RESURF lateral power device based on lateral linearly graded approximation

A novel one-dimensional(1D) analytical model is proposed for quantifying the breakdown voltage of a reduced surface field(RESURF) lateral power device fabricated on silicon on an insulator(SOI) substrate.We assume that the charges in the depletion region contribute to the lateral PN junctions along the diagonal of the area shared by the lateral and vertical depletion regions.Based on the assumption,the lateral PN junction behaves as a linearly graded junction,thus resulting in a reduced surface electric field and high breakdown voltage.Using the proposed model,the breakdown voltage as a function of device parameters is investigated and compared with the numerical simulation by the TCAD tools.The analytical results are shown to be in fair agreement with the numerical results.Finally,a new RESURF criterion is derived which offers a useful scheme to optimize the structure parameters.This simple 1D model provides a clear physical insight into the RESURF effect and a new explanation on the improvement in breakdown voltage in an SOI RESURF device.     

Influence of temperature on the accumulation of space charge in polymers by high-energy injection

An experimental investigation was made of the accumulation of space charge in polymethylmethacrylate, polystyrene, and polyethylene by injection of electrons at temperatures 120–300°K. The space charge was determined by a radiation method of probing the electric potential. An analysis of the experimental data on the basis of a phenomenological model made it possible to determine the electrical properties of the investigated insulators.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 62–65, June, 1980.     

Influence of oxidation on space charge dynamics in DC aged low-density polyethylene

In this study, low-density polyethylene (LDPE) samples were aged under different oxygen concentration (0, 20%, and 50%). The ageing was implemented with an average external DC electric field of 50 kV/mm at 40 °C for 1000 h. It was found that augmentation of charge accumulation and suppression of charge dissipation were enhanced with increasing of oxygen concentration. The capture capability of trap sites got stronger with higher oxygen contents, which could be attributed to oxidation product newly generated during DC ageing. These trap sites acted as trap centers to capture the injected carrier while it was on the way towards the opposite electrode and decrease the apparent mobility. FTIR absorption spectra showed that new elements between 1680 and 1750 cm^?1 corresponding to ketone and aldehyde occurred due to oxidation. The bipolar charge injection model was implemented to simulate space charge transport in aged LDPE samples. It was shown that more carriers were captured and the traps gradually filled up when the oxygen concentration in the ageing test increased. A higher oxygen concentration seemed to result in a deeper average trap depth, which increased the amount of trapped charge because it was not easy to detrap. These simulation result corresponded to the experimental measurement.     

二极管间隙距离对场致发射过程中空间电荷效应的影响

在强电场条件下,由阴极通过场致发射产生的电子具有很强的空间电荷效应,因此真空二极管的空间电荷限制电流是设计高功率微波源等强流电子束器件时需要考虑的重要参数.场致发射电流密度只和阴极材料、阴极表面电场等有关,而空间电荷效应则会受二极管电压、间隙距离等因素的影响.为研究二极管间隙距离对场致发射过程中空间电荷效应的影响,建立了由场致发射阴极构成的一维平板真空二极管物理模型,利用第一性原理的粒子模拟方法,研究了二极管间隙距离和外加电压等参数变化时的阴极表面电场随时间的演变特性,得到了阴极表面稳态电场和二极管间隙距离之间的关系.结果表明,场致发射过程开始后,阴极表面电场先有个振荡过程,随后趋于稳定;在同一外加电场条件下,间隙距离越长,稳态电场的绝对值越小,且达到稳态所需的时间也越长;间隙距离越短,当阴极表面电场达到稳定状态时,二极管间隙区的电场分布变化越剧烈.     

改进RCF算法的电缆绝缘层边缘检测

目前电缆绝缘层厚度检测算法主要采用图像处理技术提取出绝缘层的边缘轮廓,此类算法存在绝缘层边缘过宽和边缘不连续等问题,影响了后续的检测精度.为提高绝缘层测量精度,新算法基于RCF算法进行改进,在模型的4、5阶段采用空洞卷积,增大模型的感受野;并在侧输出网络加入尺度增强模块(SEM模块)和由浅到深的级联网络,增加侧输出图像...     

Influence of the rate of voltage rise on electrical forming and breakdown in a thin-film MIM system

An investigation was made of the influence of the rate of voltage rise on forming and breakdown in a thin-film metal-insulator-metal(MIM) system. It was found that an increase in the rate of voltage rise led to a reduction in the forming probability and consequently to an increase in the breakdown probability when the voltage exceeded a certain critical value, under otherwise identical conditions. Taking into account the known published data on forming and breakdown, the experimental results obtained were used as the basis for a qualitative model of electrical breakdown in the investigated MIM systems.Institute of Automated Control and Radio-Electronic Systems, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 95–98, November, 1992.     

Advanced Faraday cage measurements of charge and open-circuit voltage using water dielectrics

Distilled water, tap water, Sargasso Sea water and 0.9% NaCl solution contained in a Nalgene 30 ml polyallomer centrifuge tube are found to maintain distinct negative non-zero equilibrium charges as measured within a grounded patented Faraday cage. Here, the Faraday cage is composed of two identical in-line hollow, gold-plated Faraday cup electrodes which enclose the sample that moves between them during each measurement under computer control. Charge measurements using various electrometers were conducted to rule out the possibility of false instrument readings due to input offset voltage and other experimental effects. Charge, voltage and capacitance are presented as a function of the water dielectric temperature.     

Electrical breakdown of the space vacuum

The insulating properties of the vacuum of space are examined in this paper. Generic electrode configurations are introduced to calculate the leakage current to the electrodes and the breakdown potential of the “space-vacuum” as a function of altitude above ground. The condition that defines the breakdown threshold is dependent on the size of the sheath, r_L-B, relative to the interelectrode separation, r_c. Results for the leakage currents and breakdown voltage are presented for both cases r_L-B>r_e and r_L-Be, and discussed in the context of space power systems and the SPEAR Program in particular     

Effect of annealing on conductivity in XLPE mid-voltage cable insulation

A new study of the electrical conductivity of crosslinked polyethylene (XLPE) mid-voltage (MV) cable insulation is presented. Its main objective is to show the effect of annealing treatments on MV cables under actual service conditions. Complementary time domain (absorption/resorption currents) and frequency domain (dynamic electrical analysis) techniques are applied on different laboratory samples containing XLPE insulations: sections of XLPE insulated cable (with and without semiconducting screens) in the case of absorption/resorption currents and, in the case of dynamic electrical analysis, a thin ribbon obtained from the cable insulation by mechanical procedures. For annealing temperatures below a certain critical temperature, conductivity decreases both for XLPE cylinders (cable sections from which inner and outer semiconducting screens have been removed) and for real cables (sections of cable with semiconducting screens) but its value is smaller in the case of cables. If the annealing temperature is higher than the critical temperature, the behaviour of conductivity is more complex. In XLPE, cylinders conductivity initially decreases with the annealing time but after some annealing time it begins to increase, it passes over a maximum and eventually it decreases monotonically. In the case of real cable sections, conductivity grows, tending to a saturation value, which is noticeably higher than the corresponding value of the maximum obtained for XLPE cylinders. The experimental results are explained satisfactorily by means of the Mott equation that takes into account hopping conduction assisted both by temperature and electric field.     

冷绝缘高温超导电缆绝缘设计的研究

目前随着国内外高压输电系统的不断发展,许多研究机构一直试图开发高电压等级的高温超导电缆系统,这就要求设计的HTS电缆要有可靠的绝缘性能和优化的绝缘设计技术.根据超导电缆的结构特点和高温超导电缆系统的运行特点,对Nomex和PPLP进行了交流耐压、雷电冲击、局部放电(PD)起始电压和热循环等高压绝缘特性试验.根据不同厚度...     

Photoresponse at the semiconductor-electrolyte junction: Influence of the space charge region width

By varying the potential applied to a semiconductor-electrolyte junction its spectral response is modified. The definition of a reduced parameter from the ratio between two spectral responses at two different potentials is achieved. A quantitative analysis of the behaviour of the illuminated junction is then possible, as well as a comparison with the theoretical Gärtner model without the knowledge of the incident photon flux. The experimental support is provided by the n-GaP-1M HClO₄ junction where the semiconductor presents an indirect and a direct energy transition. Thus a spectral region is determined where the Gärtner model and the experimental spectrum coincide and a value of the minority carrier diffusion length (L=0.31μm) is deduced.