Double heterojunction bipolar transistors with chirped InGaAs/InP superlattice base-collector junction grown by CBE

We report the performance of InP DHBTs with a chirped InGaAs/InP superlattice B-C junction grown by CBE. The B-C junction of the DHBT was graded with a 10-period InGaAs/InP chirped superlattice (CSL) between the InGaAs base and the lightly doped InP collector. A highly doped thin layer was also included at the end of the CSL to offset the quasielectric field arising from the grade and suppress further the carrier blocking effect across the B-C heterojunction. The InP/InGaAs CSL DHBT demonstrated a high BVCEO of 18 V with a typical current gain of 55 with minimal carrier blocking up to high current densities. Maximum cutoff frequencies of f(max) = 146 GHz and f(T) = 71 GHz were obtained from the fabricated 2x10 mu m(2)-emitter DHBT.