Neutron radiation effects in GaAs ion-implanted metal-semiconductor field-effect transistors

Abstract

Neutron radiation investigations have been carried out on ion-implanted GaAs metal-semiconductor field-effect transistors (MESFETs). Device characteristics were measured before irradiation and following neutron irradiations with fluences from 5×1013 to 2×1015 n/cm2. At 5×1013 n/cm2, the device degradation is negligible, while at 2×1015 n/cm2 the threshold voltage shift was 0.7 V and the device transconductance was 30% of its original value. Degradation parameters needed to explain these results are larger than what has been previously reported; this discrepancy is, in part, due to the nonuniform doping profiles in the FET channel. The details of a new model applicable to nonuniform carrier distributions and to density dependent carrier removal rates are presented and results compared to those in the literature. A carrier removal rate of approximately 20 cm−1 is required to explain the degree of observed device degradation.