Graded base type-II InP/GaAsSb DHBT with fT = 475 GHz

Abstract

The first demonstration of a Type-II InP/GaAsSb double heterojunction bipolar transistor (DHBT) with a compositionally graded InGaAsSb to GaAsSb base layer is presented. A device with a 0.4 × 6 μm2 emitter dimensions achieves peak fT of 475 GHz (fMAX = 265 GHz) with current density at peak fT exceeding 12 mA/μm2. The structure consists of a 25-nm InGaAsSb/GaAsSb graded base layer and 65-nm InP collector grown by MBE with breakdown voltage ∼4 V which demonstrates the vertical scaling versus breakdown advantage over type-I DHBTs. © 2006 IEEE.