GaAsSb-Based DHBTs With a Reduced Base Access Distance and fT/fMAX=503/780 GHz

We report InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) with simultaneous current and power gain cutoff frequencies of f(T)/f(MAX) = 503/780 GHz. Devices with a 0.2 x 4.4 mu m(2) emitter area feature a peak DC current gain beta = 17 and a common-emitter breakdown voltage BVCEO = 4.1 V. To the best of our knowledge, the present transistors are the first GaAsSb-based DHBTs to feature f(MAX) > 750 GHz. The progress in RF performance is enabled by a reduction of the base access resistance and base-collector capacitance achieved via an improved self-aligned emitter etching procedure.