具有高压互连线的多区双RESURF LDMOS击穿特性

对600V以上级具有高压互连线的多区双RESURF LDMOS击穿特性进行了实验研究,并对器件进行了二维、三维仿真分析.利用多区P-top降场层的结终端扩展作用以及圆形结构曲率效应的影响,增强具有高压互连线的横向高压器件漂移区耗尽,从而降低高压互连线对器件耐压的影响.实验与仿真结果表明,器件的击穿电压随着互连线宽度的减小而增加,并与P-top降场层浓度存在强的依赖关系,三维仿真结果与实验结果较吻合,而二维仿真并不能较好反映具有高压互连线的高压器件击穿特性.在不增加掩模版数、采用额外工艺步骤的条件下,具有30μm高压互连线宽度的多区双RESURF LDMOS击穿电压实验值为640V.所设计的高压互连器件结构可用于电平位移、高压结隔离终端,满足高压领域的电路设计需要.     

具有部分n埋层的高压SJ-LDMOS器件新结构

针对衬底辅助耗尽效应降低常规super junction LDMOS(SJ-LDMOS)击穿电压的不足,提出了一种新的具有部分n埋层的高压SJ-LDMOS器件结构.通过该部分n埋层,不仅补偿了由于衬底辅助效应所致的电荷不平衡现象,实现了高的击穿电压,而且该埋层在器件正向导通时为电流提供了辅助通道,减小了器件导通电阻.分析了器件结构参数和参杂对器件击穿电压和导通电阻的影响,结果表明文中所提出的新结构具有高的击穿电压、低的导通电阻以及较好的工艺容差等特性.此外,该结构与智能功率集成技术兼容.     

STUDY OF MECHANISM OF BREAKDOWN IN LAMINARTURBULENT TRANSITION OF SUPERSONIC BOUNDARY LAYER ON FLAT PLATE

Spatial mode direct numerical simulation has been applied to study the mechanism of breakdown in laminar-turbulent transition of a supersonic boundary layer on a flat plate with Mach number 4.5. Analysis of the result showed that, during the breakdown process in laminar-turbulent transition, the mechanism causing the mean flow profile to evolve swiftly from laminar to turbulent was that the modification of mean flow profile by the disturbance, when they became larger, leads to remarkable change of its stability characteristics. Though the most unstable T-S wave was of second mode for laminar flow, the first mode waves played the key role in the breakdown process in laminar-turbulent transition.     

Compressible and confined vortex flow

The internal compressible flow of a thin vortex chamber was investigated experimentally by measuring the radial distribution of temperature and pressure, from which the velocity field was calculated. The bulk of the internal vortex was found to be described by u_θr^0.69 = constant. The total resistance of the vortex chamber to the flow was also investigated in the context of fluidic vortex diode behavior under conditions of compressible and choked flow. It was found that the vortex chamber choked at an upstream-to-downstream pressure ratio of about 6 and in doing so passed a mass flow rate of 28% of the equivalent one-dimensional ideal nozzle. The resistance of vortex chambers is known to be strongly influenced by the presence of reversed flow in the exit due to vortex breakdown. Schlieren photography of the swirling exhaust flow was used to show that, while vortex breakdown does occur, it can only do so after the flow has become subsonic downstream of the exit and cannot therefore influence the vortex chamber resistance.     

Laser-induced breakdown spectroscopy in analysis of Al3+ liquid droplets: on-line preconcentration by use of flow-injection manifold

Laser-induced breakdown spectroscopy (LIBS), combined with a flow-injection system, is demonstrated to analyze liquid droplets of aluminum salt, as generated with an electrospray ionization device. The spray needle also serves as the anode, through which the analyte solution is spread toward the other metal base as the cathode. Along the passage of the FI manifold, the Al-sample loading speed is controlled at 0.15 mL min⁻¹, restricted to the small diameter of the spray needle, and the loading volume amounts to 0.1 mL. The metal ion is retained in a cation-exchange resin microcolumn immobilized with Chromotrope 2B chelating agent, followed by elution with a 0.5 M HCl solution into LIBS. Upon laser irradiation at the preconcentrated liquid droplets, the time-resolved laser-induced breakdown (LIB) emission and plasma-induced current signals are acquired concurrently on a single-shot basis. The area under the LIB/current distribution increases in linear proportion as the concentration of the sample solution increases. The detection limit thus obtained can reach 1.5 mg L⁻¹, about an order of magnitude lower than those achieved previously using single-laser ablation without involvement of preconcentration. The linear dynamic range is more than two orders of magnitude.     

Development in the application of laser-induced breakdown spectroscopy in recent years: A review

Laser-induced breakdown spectroscopy (LIBS) has been widely studied due to its unique advantages such as remote sensing, real-time multi-elemental detection and none-to-little damage. With the efforts of researchers around the world, LIBS has been developed by leaps and bounds. Moreover, in recent years, more and more Chinese LIBS researchers have put tremendous energy in promoting LIBS applications. It is worth mentioning that the application of LIBS in a specific field has its special application background and technical difficulties, therefore it may develop in different stages. A review summarizing the current development status of LIBS in various fields would be helpful for the development of LIBS technology as well as its applications especially for Chinese LIBS community since most of the researchers in this field work in application. In the present work, we summarized the research status and latest progress of main research groups in coal, metallurgy, and water, etc. Based on the current research status, the challenges and opportunities of LIBS were evaluated, and suggestions were made to further promote LIBS applications.     

激光感生击穿光谱及研究现状

综述了激光感生击穿光谱技术及其研究现状。对激光感生击穿光谱的原理、特点、理论上和应用中的发展历史和现状进行了系统地介绍。理论上的研究包括激光感生等离子体内部的平衡及非平衡等问题;在应用研究上,激光感生击穿光谱开始广泛地应用于燃烧、冶金、水污染、土污染、艺术品及染料鉴定等行业,并开始有成品仪器出现。     

硼微晶玻璃片状扩散源在肖特基二极管中的应用研究

本文通过硼微晶玻璃片状扩散源在肖特基二极管中的使用过程,概述了７５×３ｍｍ硼微晶玻璃片状扩散源的扩散原理、扩散方法,实验过程;总结实验结果,给出了有关数据,讨论了存在的问题。     

掺硅对二氧化钛压敏电阻性能的影响

采取通用的陶瓷工艺,按配方(摩尔分数)TiO2+0.3%(BaCO3+Bi2O3)+0.075%Ta2O5+x%SiO2,其中x=0.1,0.2,0.3,0.4,0.5,制备试样。经过R-f,C-f和I-V测量,研究了SiO2对(Ba,Bi,Si,Ta)掺杂的TiO2基压敏陶瓷的压敏特性、电容特性及晶粒半导化的影响。结果表明:当x=0.3时,压敏电压最低(E10mA为8V.mm–1),电容量最大(C为30pF,1kHz)及晶粒电阻最小(1.4?)。     

Control of vortex breakdown in a closed cylinder with a small rotating rod

Effective control of vortex breakdown in a cylinder with a rotating lid was achieved with small rotating rods positioned on the stationary lid. After validation with accurate measurements using a novel stereoscopic particle image velocimetry (SPIV) technique, analysis of numerical simulations using a high-order spectral element method has been undertaken. The effect of a finite length rod creates additional source terms of vorticity as the rod rotates. These additional source terms and their spatial locations influence the occurrence of the vortex breakdown.