半导体材料的发展及现状

介绍了半导体材料近 1 0年来的开发、研制状况及其在半导体器件和电路中的应用 ;对其中一些材料进行了分析比较 ;描述了半导体新型材料的发展前景。     

5～10—GHz 15—W GaAs MESFET器件的设计

采用多节平调阻抗变换器技术制作5～10GHz15WGaAsMESFET功率放大器。阻抗变换器的长度设计为最高频率的1／4波长,实现宽频带内稳定的增益和输出功率。采用这种阻抗变换器,放大器在5～10GHz范围内具有9±1dB的线性增益,其1dB压缩功率为41.8±1dBm,功率附加效率为37.5±7.5％。     

旁栅阈值电压与旁栅距的关系研究

旁栅效应是制约 Ga As器件及电路性能的有害寄生效应。文中理论推导并实验研究了旁栅阈值电压 Vth SG与旁栅距 LSG的关系 ,发现 Vth SG与 LSG成正比关系。这一结论对数字电路设计具有重要指导意义 ,在设计电路版图时可根据电路的逻辑电平摆幅 VSW选择器件之间的最小距离 L     

4H-SiC MESFET高频小信号特性的模拟与分析

建立了4H-SiC MESFETs的模型,运用二维器件模拟软件MEDICI对4H-SiC MESFETs的高频小信号特性进行了研究．利用正弦稳态分析的方法对4H-SiC MESFETs的高频小信号特性进行了模拟,模拟结果与实验数值比较表明在特征频率f_T以内得到了较为满意的结果．分析了不同的栅长、栅漏间距、不同的沟道掺杂以及温度变化对SiC MESFET特征频率f_T的影响．     

Comparing the MESFET and HEMT models for efficient circuit design

In this paper, the relative advantages of several widely used MESFET and HEMT models have been compared. The nonlinear behaviours of the Curtice quadratic, Curtice cubic, Statz, Materka, Rodriguez, and Chalmers models were investigated through their current–voltage–temperature characteristics. To better fit such characteristics, neural‐based models of MESFET and HEMT were generated using a Levenberg–Marquardt back‐propagation algorithm. Close agreement was observed between simulated results and experimental data. Copyright © 2007 John Wiley & Sons, Ltd.     

半绝缘砷化镓及其MESFET器件光敏特性研究

用波长范围为 70 0～ 3 5 0 0 nm的光电流测试系统研究了 SI-Ga As衬底及其 MESFET器件中的深能级。结果显示在 SI-Ga As衬底及其 MESFET器件中存在着相似的深能级 ,衬底的深能级影响着器件的光敏等性能。还讨论了如何减少器件中光敏现象的方法。     

采用目标函数计算GaAsMESFET小信号等效电路的新方法

提出了一种计算GaAsMESFET器件小信号等效电路的简单方法。本征元件由传统解析参数变换技术计算,且作为非本征元件的函数。等效电路由集中元件构成,在整个测量频率范围内适用。非本征元件可以作为优化标准本征元件的方差,构成目标函数,进行迭代计算。在0至10GHz频宽内选取10多个不同的偏置点,计算结果与测量的S参数相吻合,表明MESFET等效电路对测量的偏置点适用     

Numerical simulation of the response of substrate traps to a voltage applied to the gate of a gallium arsenide field effect transistor

We report on a numerical simulation of the response of substrate traps to a voltage applied to the gate of a gallium arsenide field effect transistor (GaAs FET) using proprietary simulation software. The substrate is assumed to contain shallow acceptors compensated by deep levels. The ratio between the densities of deep and shallow levels is considered to be one hundred, which is a typical value for semi-insulating substrates. Although several traps may be present in the substrate but only the most commonly observed ones are considered, namely hole traps related to Cu and Cr, and the familiar native electron trap EL2. The current–voltage characteristics of the GaAs FET are calculated in the absence as well as in the presence of the above mentioned traps. It was found that the hole traps are affected by the gate voltage while the electron trap is not. This effect on the response of hole traps is explained by the fact that the quasi-hole Fermi level in the substrate is dependent on the gate voltage. However, the electron quasi-Fermi level in the substrate is insensitive to the gate voltage and therefore electron traps are not perturbed.     

S波段功率SiC MESFET(芯片)研制

介绍了一种S波段功率SiC MESFET芯片的研制技术。针对SiC材料的特点,对4H-SiC外延材料进行了设计和仿真,同时对Al记忆效应进行了研究,优化了4H-SiC外延生长技术。研究了栅长与沟道厚度纵横比(Lg/a)对短沟道效应和漏极势垒降低效应的影响。采用了凹槽栅结构和体标记电子束直写技术以及热氧化SiO2和SiNx复合钝化层设计等新制备工艺,实现了栅、漏泄漏电流的减小和源、漏击穿电压的提高。测试结果表明,功率SiC MESFET芯片在3.4 GHz频率下脉冲输出功率大于45 W,功率增益8.5 dB,漏极效率40%。测试条件为漏极工作电压48 V,脉宽100μs,占空比10%。