Breakdown Voltage Limitations, Impact Ionization, and Interband Tunneling in InP/GaAsSb/InP Type-II NpN DHBTs

摘要

We investigate the breakdown limitations of staggered ("type-II") lineup InP/GaAsSb/InP N-p-N double hetero-junction bipolar transistors (DHBTs). These devices generally feature an abnormally low open-emitter BV{sub}(CBO) despite the low electron impact ionization coefficient for electrons in the InP collector layer. We show that the high apparent BV{sub}(CEO)/BV{sub}(CBO) ratio can be associated with the onset of interband (Zener) tunneling across the narrow energy gap interface layer arising from the staggered band alignment at the reverse biased GaAsSb-InP base-collector hetero-junction. We also demonstrate that InP/GaAsSb DHBTs can be operated above BV{sub}(CEO) (and the apparent BV{sub}(CBO)), and UP to voltages approaching the impact ionization limited BV{sub}(CBO).