"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，分析了器件参数对开关特性的影响。由于人们关注的焦点是其大功率运行的能力，本文以静电感应晶闸管（SI-Th）为研究对象，为了提高器件的开关性能，特别是降低器件的局部开关损耗，器件的结构和尺寸不断变化。研究了双向短路发射极、栅区附近的分布和埋栅区的有效宽度与载流子流量、关断电流浓度和电压恢复分布的关系。为了将器件内部现象的详细分析与外部电路结构联系起来，考虑了SPICE建模方案。SITh和埋栅GTO从外部看的特性差异未作介绍。将SPICE建模所需的测量参数与器件参数联系起来，并与实验结果进行了比较。给出了一种从器件参数如寿命、杂质浓度分布和尺寸等获得SPICE等效器件参数的实用方法。本文还对直接测量方案进行了研究，并对器件结构与缓冲电路结构的最佳配合，特别是有源缓冲电路的引入作了进一步的研究。该方案可用于评估特定电路对具有特殊结构的器件的有效性。为此目的，自动优化电路参数的方法应在未来的发展。

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.