Impact of selective Al2O3 passivation on current collapse in AlGaN/GaN HEMTs

Current collapse in AlGaN/GaN HEMTs is normally attributed to charged surface states which deplete the channel in the extrinsic gate- to-drain region due to the highest electric fields in the devices. It is demonstrated that the gate-source region also plays a significant role in current collapse through the selective passivation of transistors using evaporated Al₂O₃ patterned via a lift-off process. The approach allows discriminating between the respective contributions of the source and drain regions to the current collapse.