New mechanism of gate current in heterostructure insulated gate field-effect transistors

It is demonstrated that the mechanism responsible for the gate current in heterostructure insulated gate field-effect transistors changes drastically at the gate voltage equal to the threshold voltage. At the gate voltages below the threshold voltage the gate current is determined by the thermionic emission over the Schottky barrier at high temperatures and by the thermionic field emission at low temperatures. Above the threshold the gate current is determined by the new mechanism which is the thermionic emission over the conduction band discontinuity at high temperatures and by tunneling through the AlGaAs layer at low temperatures. The model describing the gate current in the entire range of the gate voltages and device temperatures is presented.