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

Abstract

In this paper, novel InGaP/GaAs co-integrated structures consisting of a δ-doped heterojunction bipolar transistor (δ-HBT) and a doped-channel field effect transistor (DCFET) will be fabricated and demonstrated. For the δ-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 δ-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 1×100 μm 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.