Characteristics of InGaP/GaAs co-integrated δ-doped heterojunction bipolar transistor and doped-channel field effect transistor

In this paper. novel InGaP/GaAs co-integrated structures consisting of a delta-doped heterojunction bipolar transistor (delta-HBT) and a doped-channel field effect transistor (DCFET) will be fabricated and demonstrated. For the delta-HBT, the confinement effect for holes is increased and the potential spike at emitter-base heterojunction can be reduced significantly owing to the presence of delta-doped sheet at InGaP/GaAs junction. High current gain of 490 and collector-emitter offset voltage smaller than 40 mV are achieved, when a proper emitter-edge thinning design is employed. On the other hand, for a 1 x 100 mum(2) DCFET, an undoped InGaP gate layer is used to increase gate breakdown voltage, and a thin and heavy-doped GaAs channel enhances current drivability and transconductance linearity. A high gate breakdown voltage of 35 V, a maximum drain saturation current of 780 mA, a maximum transconductance of 235 mS/mm., and a wide gate voltage range larger 3 V with the transconductance larger 150 mS/mm are obtained. Consequently, the studied co-integrated devices show a promise for circuit applications. (C) 2002 Elsevier Science Ltd. All rights reserved.