SI-IMPLANTED SUBCOLLECTOR HETEROJUNCTION BIPOLAR-TRANSISTORS

npn AlGaAs/GaAs heterojunction bipolar transistors (HBTs) fabricated u sing an Si-implant to form the subcollector followed by MOCVD growth o f the remaining structure are demonstrated. The common emitter current gain of large test devices is similar to 50 at a collector current de nsity of 1.9 x l0(3) A/cm(2). The base-collector and emitter-base curr ent ideality factors are 1.08 and 1.26, respectively. Go-implantation with Se reduced the subcollector sheet resistance to 13 Ohm/square. Pa tterning of this implanted subcollector will result in a significant r eduction of extrinsic base-collector capacitance (C-bc).