Ultra-fast power switching bipolar transistors

Higher operating frequency is one of the most attractive aims for power electronic device researchers to achieve. This paper reviews two kinds of transistor structures with improved switching performance. An optimized design of gate associated transistor (GAT) with a breakdown voltage (BV_CEO) of 500 V can perform a fall time (t_f ) of 150 ns which is reduced by 55% of that of the conventional transistor. Also a newly-developed combined-structure power transistor, named center-lightly-doped-emitter gate associated transistor (CLDE-GAT), can switch even faster demonstrating a fall time of 70 ns and a storage time (t_s) of 410 ns, which is only a half of that of the GAT made in one and the same wafer. The breakdown voltage of the CLDE-GAT and the pure GAT are both 400 V. However, the fabricating processes of the GAT and the CLDE-GAT, based on the conventional triple-diffused process, are simple. So it can be concluded that ultra-fast power switching bipolar transistors can be achieved with the help of the optimized GAT structure or the further-improved CLDE-GAT structure and the advantage of low cost can still be maintained due to the simple fabrication processes