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) buffer layer are investigated as a function of device bias conditions for laser and ion irradiation. In accordance with earlier measurements, the 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 reduction of charge-enhancement mechanisms in the LT GaAs devices. It is revealed that charge-enhancement processes do occur in the LT devices under certain bias conditions, although at significantly reduced levels when compared to conventional FETs.