功率器件热性能的测试与分析

本文利用红外热像仪测温系统,系统地对三种典型的航天用功率器件进行了测试和分析。研究结果对功率器件可靠性分析具有重要的作用。同时对功率器件进行了数值模拟,在定性方面可为器件的热设计提供改进方向和合理方案。     

Three-dimensional optical logic devices using spatial multiwaveguide system

Based on the weakly coupled-mode theory, the coupled-mode equations of the spatial multiwaveguide system are presented in general. The intensity distribution in each waveguide is determined by numerical method. Optical logic devices based on spatial multiwaveguide system are proposed. The analysis results show that the spatial multiwaveguide system permits different Boolean logic states obtained by phase modulation.. Applications of the logic devices include optical calculation, optical interconnection, and spatial optical signal processing.     

Spectroscopic analysis of packaging concepts for high-power diode laser bars

Double-side cooled high-power diode laser bars packaged by different techniques on different types of passive heat sinks are analyzed in terms of packaging-induced strain. Reference data from standard devices being single-side cooled only and packaged by conventional soft and hard soldering are also presented. Thermal profiling across the devices complements the results. The most suitable packaging architecture and technique for double-side cooled bars is identified. Measurements of the laser emission near field and electroluminescence pattern provide direct reference to the functionality of the devices. Furthermore, a type of cross calibration of the methods used for strain analysis is made, since all techniques are applied to the same set of bars. This involves micro photoluminescence, micro Raman, and degree-of-polarization electroluminescence spectroscopy.     

小尺寸应变Si金属氧化物半导体场效应晶体管栅隧穿电流预测模型

小尺寸金属氧化物半导体场效应晶体管(MOSFET)器件由于具有超薄的氧化层、关态栅隧穿漏电流的存在严重地影响了器件的性能,应变硅MOSFET器件也存在同样的问题.为了说明漏电流对新型应变硅器件性能的影响,文中利用积分方法从准二维表面势分析开始,提出了小尺寸应变硅MOSFET栅隧穿电流的理论预测模型,并在此基础上使用二维器件仿真软件ISE进行了仔细的比对研究,定量分析了在不同栅压、栅氧化层厚度下MOSFET器件的性能.仿真结果很好地与理论分析相符合,为超大规模集成电路的设计提供了有价值的参考. 关键词： 应变硅 准二维表面势 栅隧穿电流 预测模型     

Spontaneous emission in longitudinal wiggler and solenoidal magnetic field

Summary In this paper we study the spectral brightness of the radiation emitted by electrons moving in longitudinal wiggler and solenoidal magnetic field. The analysis is based on the evaluation of the Lienard-Wiechert potential retaining the condition of far-field limit. Some features of a longitudinal wiggler are presented and compared with the results relevant to the brightness of the helical wiggler and the solenoidal magnetic field employed in gyrotron-type devices.     

等离子体装置中粉尘问题研究进展

等离子体装置中,带电粒子与壁材料相互作用会导致粉尘的产生。综述了主要等离子体装置中粉尘问题的实验研究现状,对主要装置中使用的诊断方法和所得到的实验结果进行了评述。提出了等离子体装置粉尘研究中存在的问题以及未来研究的方向。     

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The interactions between charged particles and wall materials produce dusts in plasma devices. Progress of dust research on the main plasma devices are reviewed, the approaches to measure dusts and the results obtained in main plasma devices in the world are presented. The unsolved problems and possible directions for further advancements are commented.     

Modelling a millimeter wave harmonic power combiner by a hybrid field analysis technique

A dual-diode millimeter wave harmonic power combiner in which two radial line transformers are used is modelled by a field analysis technique based on Galerkin's method combined with collocation technique. The external circuit impedances looking outside from each of two active devices are computed at both fundamental frequencies and the second harmonic frequencies. Numerical results of the impedances with respect to various structural parameters are presented. Some important characteristics of the harmonic power combiner are revealed. A number of useful conclusions have been deduced for practical design and adjustment.     

微流控光学器件与系统的研究进展

微流控技术作为微全分析系统的关键与核心,一直是MEMS领域中的一个研究重点。随着微流控技术水平的不断提高以及与其它学科的不断渗透与融合,近年来已经涌现出一批令人注目的研究热点,其中微流控光学器件就是其典型代表。微流控技术与光学器件的融合,为传统光学器件的微型化、阵列化、低成本化以及高精度控制提供了可能。叙述了一些基于微流控技术的可变焦光透镜、显示器件、光开关、以及可调光纤光栅等新型光学器件的近期研究成果和应用背景。     

表面注入P-top区double RESURF功率器件表面电场模型

提出表面注入P-top区double RESURF功率器件表面电场和击穿电压解析模型. 基于分区求解二维Poisson方程, 获得double RESURF表面电场的解析式. 借助此模型, 研究了器件结构参数对表面电场和电势的影响; 计算了漂移区长度和厚度与击穿电压的关系, 给出了获得最大击穿电压和最小导通电阻的途径. 数值结果, 解析结果和试验结果符合较好.     

Linear Theory of the Beam-Wave Interaction in the Arbitrary Cylindrical Cerenkov Device

The hot dispersion equation in Cerenkov devices has been derived and analyzed numerically using the self-consistent linear theory. In principle, the linear analysis can be applied to efficiently calculating all kinds of beam-wave interaction in various Cerenkov devices composed of axisymmetric slow-wave structures (SWS) with arbitrary periodic profile. Then the results for Cerenkov devices with three typical SWS profiles are presented.     

Design and Analysis of InGaN-GaN Modulation-Doped Field-Effect Transistors (MODFETs) for 90 GHz Operations

A Modulation-Doped Field-Effect Transistor (MODFET) structure having quantum wire channel realized in InGaN-GaN material system is presented. This paper presents design and analysis of a novel one-dimensional Modulation-Doped Field-Effect transistor (1D MODFET) in InGaN-GaN material system for microwave and millimeter wave applications. An analytical model predicting the transport characteristics of the proposed MODFET device is also presented. Analytical results of the current-voltage and transconductance characteristics are presented. The unity-current gain cutoff frequency (f _T) of the proposed device is computed as a function of the gate voltage V _G. The results are compared with two-dimensional GaN/AlGaN MODFET and HFET devices. The analytical model also predicts that 0.25 m channel length devices will extend the use of InGaN-GaN MODFETs to above 90GHz.     

Analysis of closely-spaced index-guided semiconductor laser. I. Multistripe devices

A detailed analysis of triple-stripe lasers incorporating index guides is presented. The relevance of multistripe laser structures for a number of applications is noted and progress in constructing these devices is briefly discussed. The properties of triple-stripe lasers are calculated as a function of stripe width and stripe separation. Light-current characteristics, near-fields and carrier concentration profiles are found for a range of devices and under differing operating conditions.     

Issues in the realization of strained-layer quantum well optoelectronic devices

Ion-beam processing is the ideal complement to modern lattice-mismatched (strained-layer) heteroepitaxy for optoelectronic device fabrication. Bandstructure engineering of optoelectronic devices through the use of lattice strain is presented, and the effects of ion-beam processing on III–V strained-layer heteroepitaxial structures are summarized. Representative results from ion-implanted optoelectronic devices are presented to illustrate these principles.     

Effects of Total-Ionizing-Dose Irradiation on Single-Event Burnout for Commercial Enhancement-Mode AlGaN/GaN High-Electron Mobility Transistors

We investigate the synergism effect of total ionizing dose(TID) on single-event burnout(SEB) for commercial enhancement-mode Al Ga N/Ga N high-electron mobility transistors. Our experimental results show that the slight degradation of devices caused by gamma rays can affect the stability of the devices during the impact of high energy particles. During heavy ion irradiation, the safe working values of drain voltage are significantly reduced for devices which have already been irradiated by ~(60)Co gamma rays before. This could be attributed to more charges trapped caused by ~(60)Co gamma rays, which make Ga N devices more vulnerable to SEB. Moreover, the electrical parameters of Ga N devices after ~(60)Co gamma and heavy-ion irradiations are presented, such as the output characteristic curve, effective threshold voltages, and leakage current of drain. These results demonstrate that the synergistic effect of TID on SEB for Ga N power devices does in fact exist.     

Generation of harmonic and intermodulation products in velocity modulation microwave devices

This paper deals with the large-signal analysis of velocity modulation microwave devices. Expressions are obtained for the harmonic and intermodulation current components of the velocity modulation devices excited by multisinusoidal microwave signals. The special case of relatively small input amplitudes is considered and the results are compared with previously published results.     

Switching of a Semiconductor Laser with Multi-Detuned Optical Inputs by Controlling Injection Current

The multistability of a Fabry-Perot semiconductor diode laser for an injection current is presented when multi-optical inputs detuned from the cavity-resonant wavelength of a semiconductor laser are injected. m+1 Multi-stable states are shown to be produced in the optical output versus injection current characteristics for m detuned optical inputs. It is shown that optical output can be switched in any one of the optical input wavelengths in a relatively fast response time by applying injection current pulses. Analytical expression based on linear stability analysis is presented to predict the switching time to free oscillating mode, and larger optical input power and detuning are effective to shorten the switching time. The results here are believed to be useful to extend wavelength switching to a scope of electronic manipulation without modulation of optical inputs and can be applicable to actual devices.     

Slow Bloch surface wave devices on porous silicon for sensing applications

A new type of biosensor using slow Bloch surface waves in photonic devices based on porous silicon is presented. After optimization of the devices, a theoretical performance study is performed and demonstrates an increase in sensitivity by a factor 10 compared to surface wave sensors based on porous-silicon multilayers. First results of the experimental realization of the sensor are also shown.