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.