CHARGE-COLLECTION CHARACTERISTICS OF GAAS HETEROSTRUCTURE FETS FABRICATED WITH A LOW-TEMPERATURE-GROWN GAAS BUFFER LAYER

The charge-collection characteristics of GaAs heterojunction-insulated -gate FETs fabricated with a low-temperature grown GaAs (LT GaAs) buff er layer are investigated as a function of device bias conditions for laser and ion irradiation. In accordance with earlier measurements, th e LT GaAs FETs of this study exhibit a significant reduction in charge -collection efficiencies when compared to those of conventional FETs. This reduction in collected charge is associated with the efficient re duction of charge-enhancement mechanisms in the LT GaAs devices. It is revealed that charge-enhancement mechanisms processes do occur in the LT devices under certain bias conditions, although at significantly r educed levels when compared to conventional FETs.