AlGaN/GaN Schottky-Gate HEMTs With UV/O₃-Treated Gate Interface

Abstract

The surface condition under gate of AlGaN/GaN heterostructure plays a critical role in high-electron mobility transistor (HEMT). In this study, the effects of ultraviolet/ozone (UV/O3) treatment applied to Al0.3 Ga0.7 N/GaN heterostructure on the electrical performance of AlGaN/GaN Schottky-gate HEMT were investigated. The reverse-bias leakage current of Schottky diode was reduced by three orders after the treatment. X-ray photoelectron spectroscopy confirms the formation of the Ga2O x layer which serves as an interface passivation layer and thus suppresses trap-assisted electron tunneling. Capacitance–voltage measurements of AlGaN/GaN HEMT show shifts of threshold and on-set voltages, indicating decreased surface states as a result of the treatment. The electrical characteristics of AlGaN/GaN HEMT exhibit improved transconductance and subthreshold swing values after the treatment.