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 heterojunction 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 heterojunction. 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/.