Applying Improved Electrical Breakdown Model to Study Insulating Property of c-C_4F_8/N_2 Gas Mixture

Perfluorocyclobutane(c-C4F8) has been recently considered as a potential alternative to SF6,because of its high electro-negativity and extremely low environmental effect.However,due to its high boiling point,c-C4F8 should mixed with buffer gases such as N2 or CO2 in order to avoid the liquefaction at low temperature.This paper investigates insulating properties of c-C4F8/N2 gas mixtures from two aspects including electrical strength,and Global Warming Potential(GWP).Moreover,improved electrical breakdown model of gas mixtures is founded.Breakdown temperature and breakdown electrical field in gas mixtures can be obtained from rigorous Townsend criterion expression according to gas mixtures ratio and cross section data of gas mixtures in this model.Under the condition of different gas pressure(0.1~0.4 MPa),gas mixtures ratio(0～30%),and electrode gap(2~10 mm),breakdown voltages of gas mixtures are calculated by using of this model.Insulation strength of SF6/N2 mixed gas is compared with c-C4F8/N2 mixed gas in the same conditions.Research results show that theoretical computation corresponds with experiment.If the content of c-C4F8 or SF6 in mixtures is less than 30%,insulation strength between c-C4F8/N2 and SF6/N2 is very close.Considering two indexes(breakdown voltage,GWP),it is suitable for c-C4F8 content being 15%～20% in c-C4F8/N2 gas

Breakdown voltage model and structure realization of a thin silicon layer with linear variable doping on a silicon on insulator high voltage device with multiple step field plates

Based on the theoretical and experimental investigation of a thin silicon layer（TSL） with linear variable doping（LVD） and further research on the TSL LVD with a multiple step field plate（MSFP）,a breakdown voltage（BV） model is proposed and experimentally verified in this paper.With the two-dimensional Poisson equation of the silicon on insulator（SOI） device,the lateral electric field in drift region of the thin silicon layer is assumed to be constant.For the SOI device with LVD in the thin silicon layer,the dependence of the BV on impurity concentration under the drain is investigated by an enhanced dielectric layer field（ENDIF）,from which the reduced surface field（RESURF） condition is deduced.The drain in the centre of the device has a good self-isolation effect,but the problem of the high voltage interconnection（HVI） line will become serious.The two step field plates including the source field plate and gate field plate can be adopted to shield the HVI adverse effect on the device.Based on this model,the TSL LVD SOI n-channel lateral double-diffused MOSFET（nLDMOS） with MSFP is realized.The experimental breakdown voltage（BV） and specific on-resistance（R on,sp） of the TSL LVD SOI device are 694 V and 21.3 ·mm 2 with a drift region length of 60 μm,buried oxide layer of 3 μm,and silicon layer of 0.15 μm,respectively.

A three-dimensional breakdown model of SOI lateral power transistors with a circular layout

This paper presents an analytical three-dimensional breakdown model of SOI lateral power devices with a circular layout. The Poisson equation is solved in cylindrical coordinates to obtain the radial surface potential and electric field distributions for both fully- and partially-depleted dr/ft regions. The breakdown voltages for N＋N and P＋N junctions are derived and employed to investigate the impact of cathode region curvature. A modified RESURF criterion is proposed to provide a design guideline for optimizing the breakdown voltage and doping concentration in the drift region in three dimensional space. The analytical results agree well with MEDICI simulation results and experimental data from earlier publications.

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.

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.

Validity of the two-term Boltzmann approximation employed in the fluid model for high-power microwave breakdown in gas

The electron energy distribution function （EEDF）, predicted by the Boltzmann equation solver BOLSIG＋ based on the two-term approximation, is introduced into the fluid model for simulating the high-power microwave （HPM） breakdown in argon, nitrogen, and air, and its validity is examined by comparing with the results of particle-in-cell Monte Carlo collision （PIC/MCC） simulations as well as the experimental data. Numerical results show that, the breakdown time of the fluid model with the Maxwellian EEDF matches that of the PIC/MCC simulations in nitrogen; however, in argon under high pressures, the results from the Maxwellian EEDF were poor. This is due to an overestimation of the energy tail of the Maxwellian EEDF in argon breakdown. The prediction of the fluid model with the BOLSIG＋ EEDF, however, agrees very well with the PIC/MCC prediction in nitrogen and argon over a wide range of pressures. The accuracy of the fluid model with the BOLSIG＋ EEDF is also verified by the experimental results of the air breakdown.

基于BIM的公路工程标准化EBS分解方法

工程结构分解(EBS)是公路工程全寿命周期信息化管理的基础。为了提高公路工程建设期信息化水平,基于BIM技术应用,提出了公路工程标准化EBS分解方法。标准化分解方法根据工程中不同路段,梳理专业划分以及空间位置划分原则,并依据行业标准,确定标准化EBS结构的叶子节点,提供公路工程EBS结构树模板示例。研究结果旨在提高高速公路数字化交付中的数据处理标准建设,为实施公路工程数字化提供基础支持。

红外偏振辐射模型对铬和铜元素的优化识别

针对优化激光诱导击穿光谱技术识别铬和铜元素的问题,本文提出了一种结合红外偏振检测理论的方法。利用菲涅尔反射定律和基尔霍夫理论分析了红外偏振产生机理,根据能量守恒定律验证了目标红外自发热辐射的偏振特性;利用红外偏振辐射传输模型及菲涅尔反射穆勒矩阵,结合温度的麦克斯韦-玻尔兹曼分布特性,推导出了等离子体红外偏振辐射信号模型,用于识别各激发能量下的重金属元素;利用5种不同能量的脉冲激光验证了模型的精准性。结果表明:在相同的激光能量下,红外偏振辐射光谱可以收集到更多的特征信号峰;在低能量激励下,红外偏振辐射光谱的优势更为突出。红外偏振辐射模型的构建是科学有效的,可用于优化重金属元素的快速检测。

雪崩晶体管电压斜坡触发模式下终端失效机理研究

随着超宽带脉冲信号系统在新能源汽车智能化感知技术等许多重要领域的应用,高幅值、快前沿脉冲源的研发得到了广泛研究。针对纳秒级前沿脉冲对超快功率半导体开关的需求,进行了雪崩晶体管在电压斜坡触发模式下终端失效机理的研究。利用仿真模型的静态特性与器件样品进行对比分析,测试了器件样品的动态开通特性。在成功得到纳秒级开通速度器件的基础上,对器件在电压斜坡触发模式下出现的失效现象进行了分析。

具有两阶段故障的流模型近似解分析

本文分析了具有两阶段故障策略的流模型近似解.系统首次遭遇故障时将进入部分故障期,期间缓冲器以较低服务速率继续提供服务.若在部分故障期内缓冲器再次遭遇故障,则完全停止工作.对于具有此策略的流模型,借助归一化技术(Uniformization Technique),通过递推得到了该流模型库存量尾分布的近似解,并给出了库存量的各阶矩.最后将该流模型应用于云计算服务中由硬件故障而导致的排队分析中,利用数值例子分析系统参数对整体系统性能指标的影响.

中频真空电弧边缘击穿现象及仿真研究

为深入掌握航空变频(360~800 Hz)电力系统中真空电器电弧特性,该文围绕中频灭弧室弧后发生的边缘击穿现象,以双温磁流体动力学仿真结合实验的研究方法,得到了以下结论:中频真空电弧离子数密度的最大值为2.6×10^(19)m^(-3),离子温度的范围为0.30~0.91eV,电子温度的范围为1.50~2.43 eV;电子与离子之间存在能量交换,电子温度的变化会引起离子温度的变化;最高离子温度出现在阳极触头边缘处,与实验发现的边缘击穿位置重合,证明了此处确实存在能量集中;中频真空电弧是超声速流体,速度在边界处减慢,根据动能热能互换原理,中频真空电弧的质量流运动规律是边缘击穿的本质原因。

Small-signal modeling of GaN HEMT switch with a new intrinsic elements extraction method

A novel and accurate method is proposed to extract the intrinsic elements of the GaN high-electron-mobility transistor（HEMT） switch.The new extraction method is verified by comparing the simulated S-parameters with the measured data over the 5-40 GHz frequency range.The percentage errors E（ij） within 3.83% show the great agreement between the simulated S-parameters and the measured data.

Effect of air breakdown on microwave pulse energy transmission

The energy transmission of the long microwave pulse for the frequency of 2.45 GHz and 5.8 GHz is studied by using the electron fluid model, where the rate coefficients are deduced from the Boltzmann equation solver named BOLSIG＋. The breakdown thresholds for different air pressures and incident pulse parameters are predicted, which show good agreement with the experimental data. Below the breakdown threshold, the transmitted pulse energy is proportional to the square of the incident electric field amplitude. When the incident electric field amplitude higher than the breakdown threshold increases,the transmitted pulse energy decreases monotonously at a high air pressure, while at a low air pressure it first decreases and then increases. We also compare the pulse energy transmission for the frequency of 2.45 GHz with the case of 5.8 GHz.

Effect of microwave frequency on plasma formation in air breakdown at atmospheric pressure

Microwave breakdown at atmospheric pressure causes the formation of a discrete plasma structure. The onedimensional fluid model coupling Maxwell equations with plasma fluid equations is used to study the effect of the microwave frequency on the formation of air plasma. Simulation results show that, the filamentary plasma array propagating toward the microwave source is formed at different microwave frequencies. As the microwave frequency decreases, the ratio of the distance between two adjacent plasma filaments to the corresponding wavelength remains almost unchanged（on the order of 1/4）, while the plasma front propagates more slowly due to the increase in the formation time of the new plasma filament.

Hybrid classification of coal and biomass by laser-induced breakdown spectroscopy combined with K-means and SVM

Laser-induced breakdown spectroscopy(LIBS) is a new technology suitable for classification of various materials. This paper proposes a hybrid classification scheme for coal, municipal sludge and biomass by using LIBS combined with K-means and support vector machine(SVM)algorithm. In the study, 10 samples were classified in 3 groups without supervision by K-means clustering, then a further supervised classification of 6 kinds of biomass samples by SVM was carried out. The results show that the comprehensive accuracy of the hybrid classification model is over 98%. In comparison with the single SVM classification model, the hybrid classification model can save 58.92% of operation time while guaranteeing the accuracy. The results demonstrate that the hybrid classification model is able to make an efficient, fast and accurate classification of coal, municipal sludge and biomass, furthermore, it is precise for the detection of various kinds of biomass fuel.

Numerical Study on Atmospheric Pressure DBD in Helium:Single-breakdown and Multi-breakdown Discharges

A 1-D fluid model for homogeneous dielectric barrier discharge （DBD） in helium is presented, aimed at unraveling the spatial-temporal characteristics of two basic discharge regimes： single-breakdown and multi-breakdown discharges. Discharge currents, gap voltages, charge densities, electron temperature and electric field profiles of the two regimes make it clear that these two regimes are qualitatively different. It is found that the multi-breakdown discharge has a more homogeneous flux on dielectrics compared to the single-breakdown discharge.

集成电路HPM损伤机理分析

针对几种常用的数字和模拟集成电路,开展了高功率微波注入实验研究,获得了损伤阈值,分析了损伤阈值随高功率微波脉冲宽度的变化规律;通过失效分析,确定了高功率微波在集成电路微米量级的端间间隙处形成瞬态强电场,引起端间沿面击穿,并形成自持放电产生等离子区,使击穿电路端间大面积过流烧毁,导致集成电路功能失效;结合大气击穿机理及理论模型计算结果,认为高功率微波引起介质表面空气击穿是其损伤电子系统的重要机理。

Air breakdown induced by the microwave with two mutually orthogonal and heterophase electric field components

The air breakdown is easily caused by the high-power microwave, which can have two mutually orthogonal and heterophase electric field components. For this case, the electron momentum conservation equation is employed to deduce the electric field power and effective electric field for heating electrons. Then the formula of the electric field power is introduced into the global model to simulate the air breakdown. The breakdown prediction from the global model agrees well with the experimental data. Simulation results show that the electron temperature is sensitive to the phase difference between the two electron field components, while the latter can affect obviously the growth of the electron density at low electron temperature amplitudes. The ionization of nitrogen and oxygen induces the growth of electron density, and the density loss due to the dissociative attachment and dissociative recombination is obvious only at low electron temperatures.

Modeling,fabrication and measurement of a novel CMOS UV/blue-extended photodiode

A new complementary metal oxide semiconductor UV/blue-extended photodiode was presented for light detection in the UV/blue spectral range. Photoelectric characteristics of this presented photodiode were studied by numerical modeling and device simulation. Technology computer aided design simulation was done first to analyze its photoelectric characteristics. The structure characteristic and depletion situation of space between two adjacent P+ anodes were discussed. The reverse characteristic, spectral response characteristic and DC characteristic were discussed in detail. For the numerical modeling, dead layer effect is considered in the building of analytical mode. Dead layer is a space in which the boron doping profile decreases towards the surface due to high doping effects and boron redistribution, which affects the sensitivity of photodiode in the UV range seriously. Reverse characteristics and spectral response characteristics were modeled and analyzed typically. At last, silicon test results were given and compared with the simulated result, which shows reasonable match for each.

基于PCA-SVM的飞机蒙皮激光分层除漆LIBS在线监测研究

飞机蒙皮激光除漆过程的在线监测,是实现分层可控除漆、满足适航维修要求的重要手段,也是推进激光除漆工程应用、飞机维修自动化的核心技术。激光诱导击穿等离子体光谱(LIBS)技术可通过激光材料作用过程中产生的等离子体发射光谱快速分析材料表面元素变化,实现激光清洗表面状态的在线监测。基于搭建的高频纳秒红外脉冲激光除漆LIBS在线监测平台,分别采集了不同激光功率下,面漆、底漆、铝合金基体去除过程中的3类LIBS光谱(各100幅)。分析了不同激光功率下,各类光谱示踪元素特征谱线的变化情况,初步筛选了12条特征谱线作为光谱识别的特征。进一步对这12个特征进行主成分分析(PCA),并将前3个主成分(PC1、 PC2、 PC3)构成的数据集作为支持向量机(SVM)识别模型的输入量,建立了3类光谱的识别模型。形成了多漆层结构激光分层可控清除过程的LIBS在线监测判定规则,并对该规则的有效性进行了实验验证。结果表明,与低频脉冲激光单点作用采集的针状LIBS光谱相比,基于该平台采集的LIBS光谱普遍存在较强的连续背景(大于5 000 a.u.)以及1.5 nm左右的半峰全宽;针对此类光谱设计了改进均值平滑滤波算法,在去除背景光谱的同时有效避免了特征谱线强度失真;示踪元素的特征谱线存在不稳定性;主成分分析中前3个主成分PC1、 PC2、 PC3对光谱的解释率达95%,在其构成的三维空间中,同类光谱呈区域性聚集;PCA-SVM模型对训练集、测试集的识别准确率分别为99.44%、 100%;验证实验结果表明3类光谱的识别模型与在线监测判定规则有效。所建立的识别模型与判定规则,可为飞机蒙皮激光分层除漆过程监测及自动化解决方案提供核心技术支撑。