Gate formation in GaAs MESFET's using ion-beam etching technology

The use of ion-beam etching for the controllable formation of very thin active channel layers in GaAs MESFET's is investigated and compared with chemical and plasma etching techniques. The Schottky gate diodes associated with ion-beam etched surfaces show significant surface damage, a substantial part of which can be removed by annealing. Typical annealed diodes exhibit a barrier height of 0.53 eV and an ideality factor of 1.22. A modified Schottky theory is presented which includes the effects of surface damage and a thin interfacial layer between the metal and semiconductor. This model appears to account for most of the observed behavior. Capacitance-voltage-and current-voltage characteristics are presented for both large-area diodes on ion-beam etched surfaces and for MESFET's with gate lengths of 3 and 0.15 µm.