Roles of shallow and deep electron traps causing backgating in GaAs metal-semiconductor field-effect transistors

In GaAs metal-semiconductor field-effect transistors under backgating conditions, electrons can be trapped in ‘‘shallow’’ and deep trap levels. It is shown that the characteristics of these traps can be determined and those responsible for backgating can be identified by examining the thermally excited emission currents under zero-bias short-circuit conditions. It is established, for the first time, that there are ‘‘shallow’’ traps located under the field-effect transistor active channel, and possibly related to the ion-implantation damage, that are directly related to the backgating, although the process is initiated due to filling of deep levels by electrons near the surface of the semi-insulating GaAs.