High-speed InP/InGaAs heterojunction phototransistors with emitter metal reflector

摘要

This paper reports the characteristics of InP/InGaAs heterojunction phototransistors (HPTs) in which light is incident through the substrate. These HPTs have a base terminal and a non-alloyed emitter metal reflector that increases the quantum efficiency to 37% regardless of the thin base and collector light-absorbing layers. An optical gain of more than 70 and an optical gain cutoff frequency (f/sub c/) of 22 GHz are obtained at the 3/spl times/3 /spl mu/m/sup 2/ emitter HPT. This HPT has the capability of operating as a high-speed heterojunction bipolar transistor (HBT) at the same time. A current gain cutoff frequency (f/sub T/) of 128 GHz is obtained for HBTs fabricated on the same wafer.