A novel partial silicon on insulator high voltage LDMOS with low-k dielectric buried layer

A novel partial silicon-on-insulator (PSOI) high voltage device with a low-k (relative permittivity) dielectric buried layer (LK PSOI) and its breakdown mechanism are presented and investigated by MEDICI.At a low k value the electric field strength in the dielectric buried layer (E I) is enhanced and a Si window makes the substrate share the vertical drop,resulting in a high vertical breakdown voltage;in the lateral direction,a high electric field peak is introduced at the Si window,which modulates the electric field distribution in the SOI layer;consequently,a high breakdown voltage (BV) is obtained.The values of EI and BV of LK PSOI with kI=2 on a 2 μm thick SOI layer over 1 μm thick buried layer are enhanced by 74% and 19%,respectively,compared with those of the conventional PSOI.Furthermore,the Si window also alleviates the self-heating effect.     

SiC光导开关衬底与电极界面场强仿真与优化设计

研究电极结构、SiC与电极连接结构对界面场强的影响,通过电极边缘以及SiC晶体结构的优化降低界面处的电场增强,并通过高压试验测试优化电极结构的击穿电压。结果表明,优化电极倒角以及SiC晶体与电极的界面下埋可有效降低电场增强,在电极为圆倒角及界面使用焊料连接的结构下,使用介质环的器件在电压22 kV时击穿。     

A modified Paschen law for the initiation of a dc glow discharge in inert gases

Breakdown of inert gases in a homogeneous dc electric field is studied experimentally and theoretically at various distances L between the electrodes and radii R of the discharge tubes. It is shown that, for arbitrary geometric dimensions of the discharge chamber and cathode materials, the ratio of the breakdown electric field strength to the gas pressure holds constant at the breakdown curve minimum. A modified Paschen law is obtained, according to which the breakdown voltage is a function of both the product of the gas pressure by the distance L and the ratio L/R.     

地闪雷电电磁脉冲在大地中的分布研究

为研究地闪雷电电磁脉冲(LEMP)在大地中的分布规律,采用二维时域有限差分法计算了在雷电通道不同距离处、不同大地电参数条件下LEMP在地下不同深度的分布,并与其他高功率电磁环境在大地中的衰减情况作了对比.计算结果表明:随距离增大,大地中LEMP场分量迅速衰减;大地电导率较大时,电场分量衰减很大;大地电容率的变化主要影响LEMP的垂直电场分量,随大地电容率的增大,垂直电场分量明显减小;随深度的增大,电场分量衰减增大,其高频成分的衰减尤为显著,低频成分则衰减很小.由此可知,对电线电缆实施简单的埋地处理并不能有效防止LEMP的耦合效应.     

Experimental and modelling study of the dependence of corona discharge on electrode geometry and ambient electric field

The results of experimental observations and mathematical modeling of corona formation on the tips of grounded rods are presented as a function of their tip height, curvature radius, the magnitude and polarity of the applied electric field producing corona. The investigations demonstrate that corona current depends on the active volume of zone in which electric field strength exceeds the breakdown criteria for air. The mathematical model was verified with the experimental data, enabling dependence of corona current on rod tip height, tip radius and applied electric field strength to be quantified with the need for a plethora of experiments.     

Influence of space charge related to water trees on the breakdown voltage of power cable insulation

A three-dimensional computation of the electric field and breakdown voltage in power cable insulation containing water trees and space charges is presented. The breakdown voltage and the conductivity of cylindrical samples of cable insulation containing water trees were measured. The samples have been aged in wet environment under ac voltages of frequencies comprised between 1 and 5 kHz. Exponential and parabolic spatial variations of permittivity and space charge density and the electrostatic, electro-kinetic and quasi-stationary regimes of the electric field were considered. The best correlation between the experimental breakdown voltage and the calculated one has been obtained in quasi-stationary regime.     

Local fields in a soft matter bubble

The electric field created by a point dipole located in a dielectric void (“bubble”) is calculated. We consider a continuous profile of the medium permittivity and find that, at large distances, the effective dipole field depends on the model chosen for the bubble walls, in particular their thickness. A boundary layer model is analyzed that gives good agreement with numerical calculations. Our results shed light on the local field correction that has attracted lot of interest lately.     

μs级负充电时不同体积分数去离子水与乙二醇混合液电性能的实验研究

 以去离子水与乙二醇的混合液（体积分数分别为36.5%,48.7%,59.0%及71.2%，以下简称混合液）作为同轴传输线的绝缘介质，进行了μs级高电压负充电条件下的正电极击穿实验，研究了混合液的击穿电压、击穿时间、相对介电常数及电阻率与体积分数的关系。实验结果表明：在充电电压为20kV时，71.2%的混合液比36.5%的混合液的平均击穿电压提高25.1%，平均击穿时间延长10.49%，而相对介电常数减小868%。同时，随着充电时间的缩短，混合液的击穿电压提高。     

The effect of polymer type on electric breakdown strength on a nanosecond time scale

Based on the concepts of fast polarization,effective electric field and electron impact ionization criterion,the effect of polymer type on electric breakdown strength(E BD) on a nanosecond time scale is investigated,and a formula that qualitatively characterizes the relation between the electric breakdown strength and the polymer type is derived.According to this formula,it is found that the electric breakdown strength decreases with an increase in the effective relative dielectric constants of the polymers.By calculating the effective relative dielectric constants for different types of polymers,the theoretical relation for the electric breakdown strengths of common polymers is predicted.To verify the prediction,the polymers of PE(polyethylene),PTFE(polytetrafluoroethelene),PMMA(organic glass) and Nylon are tested with a nanosecond-pulse generator.The experimental result shows E BD(PTFE) > E BD(PMMA) > E BD(Nylon) > E BD(PE).This result is consistent with the theoretical prediction.     

百kV/cm场强下SF6气体开关纳秒脉冲击穿场强和时延经验公式

百kV/cm高场强纳秒脉冲条件下,采用J. C. Martin经验公式估算SF₆气体击穿场强时,估算值与实验结果差异显著。为了进一步指导高场强脉冲气体开关设计,为开关工作状态调节提供依据,借鉴经典击穿场强经验公式形式建立了百kV/cm场强下SF₆气体开关纳秒脉冲击穿场强和时延与实验参数之间的关系,基于实验数据拟合形成了修正系数的击穿场强和时延经验公式。研究表明,百kV/cm场强和纳秒脉冲条件下脉冲电压斜率对开关击穿特性有重要影响,击穿场强与击穿时延相互关联。百ns至μs脉冲与几十ns脉冲气体放电机理的区别引起放电过程中击穿时延组成发生变化,导致了经典击穿场强经验公式估算值与实验结果的显著差异。修正系数的击穿经验公式可为电磁脉冲模拟器输出开关提供更为精确的工程设计依据。     

Drift of excitons in an inhomogeneous electric field in silicon at 4.2K

The results are presented of the experimental detection and investigation of the phenomenon of the drift of excitons in an inhomogeneous electric field. The investigations were performed on silicon structures with Shottky barriers at 4.2 K. A study was made of the influence of the photoexcitation intensity and electric field strength on the breakdown dynamics of the structure. The experimental results were used to show that breakdown of a reverse-biased Shottky barrier involves a narrowing of the width of the space-charge region due to a drift of excitons in the inhomogeneous electric field and to recombination of electrons on ionized impurity centers of the barrier. Kh. I. Amirkhanov Physics Institute, Dagestan Scientific Center, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 67–69, May, 1997.     

微扰实验法测试螺旋线行波管耦合阻抗及模拟仿真

 应用有限元仿真软件HFSS,建立了准确的3维螺旋线行波管耦合阻抗仿真模型。应用该模型,对微扰实验法在微扰杆内电场所做出的4个假设和近似,进行了定量的分析和讨论：电场在轴向是均匀的,忽略掉轴向高次空间谐波的存在;电场在角向是均匀的,忽略掉角向高次空间谐波的存在;忽略掉电场中TE波部分,认为电场角向分量为零;假设微扰前后的电场是相等的。同时,对微扰杆的尺寸和介电常数与耦合阻抗的依赖关系进行了模拟分析。结果表明：当微扰法所引入的假设和近似逐步消失后,微扰法的结果最后收敛于定义法。     

A model for the dependence of the dielectric loss factor of a ferroelectric on the microwave signal amplitude

The nonlinear phenomena occurring in ferroelectrics were studied using a model for the dependence of the ferroelectric polarization on the amplitude of the applied field. The inclusion of the static internal defect field made it possible to determine the dependence of the complex permittivity of a ferroelectric on the dc electric field strength. The dependences of the complex permittivity and the dielectric loss factor on the amplitude of microwave oscillations were obtained using the Poynting theorem for harmonic microwave oscillations.     

Effect of mechanical stresses on the dielectric response of PZT ferroelectric thin films

This paper reports on the results of the investigation into the effect of mechanical stresses on the dielectric properties of PZT ferroelectric thin films. An external load G applied to the sample brings about an increase in the residual tensile stress along one of the axes of the film. It is demonstrated that, in weak and moderate electric fields, an increase in the stress σ leads to an increase in the permittivity ε′ of the sample. A further increase in the strength of the measuring electric field results in the opposite effect: the permittivity ε′ decreases with increasing external load G. The observed effects are explained in terms of the specific features revealed in the behavior of the domain structure of the ferroelectric thin films in fields of internal stresses.     

电场作用下的气泡受力分析

本文在蠕动流近似的基础上分析计算了具有不同介电常数工质的气泡在外电场力作用下的受力状况。计算结果表明电场力的水平分力使气泡沿场强方向伸长,并且液体和气体相对介电常数之比越大的工质所受的电场力越大。从而,沸腾换热过程中外加电场对液体和气体相对介电常数比值较大的工质能够产生更大的影响。     

Effective permittivity of the system of metal nanoislands in strong electric fields

The effect of the electric field on the value and sign of the low-frequency effective permittivity of metal island films is studied. It is shown that the permittivity in island metal films can be both positive and negative. The permittivity of some samples changed sign with the polarity of the applied electric field. Film polarization mechanisms are considered.     

Electrical breakdown of thin polymer films

Data are presented on the dielectric strength of thin polymer films. The conclusion is drawn that the electron avalanche concept is inapplicable to the breakdown of thin films. It is proposed to consider electrical breakdown as a consequence of an abrupt local field enhancement induced by evolution of the space charge injected into the polymer from electrodes. It is shown that the lifetime of polymer films depends exponentially on electric field strength.     

不同工质中汽泡周围电场特性研究

为探明外加电场作用下,不同工质对强化沸腾换热的影响,本文采用了FC-72、R11、R113和R123四种工质,定量研究了两相系统中汽泡周围电场分布特性,探讨了工质介电常数对汽泡的作用规律．结果表明:随着工质介电常数的增加,电场非均匀性增强,电场对汽泡的作用加剧．这为不同工质对EHD沸腾强化效果不同提供了理论依据．     

电极材料及偏压极性对氧化物介质击穿行为的影响及机制

忆阻器和能量存储电容器具有相同的三明治结构,然而两个器件需要的操作电压有明显差异,因此在同一个器件中,研究操作电压的影响因素并对操作电压进行调控,实现器件在不同领域的应用是十分必要的一个工作.本文利用反应磁控溅射技术在ITO导电玻璃、Pt/Si基底上生长了多晶ZrO_2和非晶TaO_x薄膜,选用不同金属材料Au, Ag和Al用作上电极构建了多种金属/氧化物介质/金属三明治结构的电容器,研究了器件在不同偏压极性下的击穿强度.结果发现:底电极是ITO的ZrO_2基电容器在负偏压下的击穿电场比Pt电极器件稍大.不管底电极是ITO还是Pt, Ag作为上电极时器件的击穿强度均存在明显的偏压极性依赖性,正偏压下的击穿电场减小了一个数量级;相反,在Al作为上电极的Al/TaO_x/Pt器件中,正向偏压比负向偏压下的击穿电场增加了近2倍.上述器件的不同击穿行为分别可以由氧化物电极和介质界面层间氧的迁移和重排、电化学活性金属电极的溶解迁移和还原以及化学活性金属电极与氧化物界面的氧化还原反应来解释.该实验结果对有不同操作电压要求的器件,如忆阻器和介质储能电容器等在器件设计和操作方面具有指导意义.     

Effect of the duration of the front edge of the voltage pulse on the electric breakdown of ammonium perchlorate

The results of a study of the effect of the front edge duration of a voltage pulse (τ) on the electric breakdown of ammonium perchlorate single crystals are submitted. Experiments have shown that at τ<1.5 µs, the breakdown threshold field increases with reduction in τ and does not depend on τ at τ>1.5 µs. It is shown that the electric breakdown of ammonium perchlorate results from an impact generation of electrons. The impact generation rate of electrons versus electric field and the diameter of the through channel being formed during electric breakdown in ammonium perchlorate are estimated.