Reduction of threshold voltage instability in recessed-gate AlGaN/GaN MOSHEMTs by KOH passivation

GaN-on-Si MOSHEMTs are fabricated with gate-recessed structure. It is found that surface damages introduced by plasma bombardment during recess etch at oxide-semiconductor interface cause instability of threshold voltage of the devices. To eliminate the surface damages, KOH passivation is applied and the effect is studied in this report. Hysteresis is inhibited and the flat-band voltage shift reduces from 0.3 V to 0.16 V with KOH treatment in the C-V characteristics. Drain currents of the passivated devices also enhance 33 % under the same overdrive voltages.