"Optimization of Switching Characteristics of High-Power Static Induction (SI) devices"

利用作者开发的大功率开关半导体器件仿真程序，研究了静电感应功率器件的开关特性，并分析了开关特性对器件参数的依赖关系。由于对其大功率工作能力的关注，本文以静态感应晶闸管（SI-Th）为分析对象。为了提高开关性能，特别是降低局部开关损耗，器件的结构和尺寸是多种多样的。研究了双向短路发射极、近栅区分布和埋栅区有效宽度与载流子流量、关断时电流浓度和电压恢复分布的关系。根据仿真结果，给出了它们的作用和改进设计的建议。为了将器件中这种现象的详细分析与外部电路结构联系起来，考虑了使用SPICE的建模方案。本文没有介绍从外部看，sit与埋栅GTO的特性差异。将SPICE建模所需的测量参数与器件参数相关联，并与实验结果进行比较。给出了一种从器件寿命、杂质浓度分布、尺寸等参数求出等效器件参数的实用方法。并对直接测量方案进行了研究。器件结构与缓冲器电路配置之间的最佳协调，特别是与有源缓冲器的引入有关，需要进一步研究。本文提出的方案有助于评估特定电路对具有特殊结构的器件的有效性。今后应进一步发展自动优化电路参数的方法。

Utilizing the device simulation code for high power switching semiconductor device developed by the authors, the switching characteristics of the static induction power devices are studied and their dependency on parameters of the devices is analyzed. Since the interests are focused on their ability in high power operation, the static induction thyristor (SI-Th) is taken up as the object analyzed.To improve the switching capabilities, especially local switching loss reduction, the structure and dimension of the device are varied. The two-directional shorting emitter, the profile near gate area and the effective width of the buried gate region are studied in relation with carrier flow, current concentration during switching-off and the profile of the voltage recovery. Their effects and suggestions to the improvement of the design are given from the simulation results.In order to relate such detailed analysis of the phenomenon in the device with the outer circuit construction too, the modeling scheme with SPICE is considered. The difference of the characteristics viewing from outside between SITh and buried gate GTO is not so introduced. The measured parameters required for the modeling with SPICE are made to be related with device parameters and compared with the experimental results. A practical way to obtain equivalent device parameter of SPICE from the device parameters such as life times, impurity concentration distribution and dimensions is shown. Thedirect measuring scheme is also studied.Further study is required on the optimal coordination between device structure and the snubber circuit configuration, especially in relation with the introduction of the active snubber. The scheme developed here is useful to evaluate the effectiveness of the specific circuit against the device with a special structure. The method to optimize automatically the circuit parameters for this purpose should be developed in future.