Al_0.25Ga_0.75N/GaN enhancement-mode MOS high-electron-mobility transistors with Al₂O₃ dielectric obtained by ozone water oxidization method

Al_0.25Ga_0.75N/GaN enhancement-mode (E-mode) metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) obtained by the ozone water oxidization method are investigated in this work. Decreased gate leakage and reduced channel depletion are obtained by forming the Al₂O₃ dielectric layer of the MOS gate structure by a cost-effective oxidization method. Pulse current-voltage (I-V), low-frequency noise, and Hooge coefficient measurements are compared to verify the interface quality improved by the oxide passivation effect. In comparison, a conventional Schottky-gate HEMT device is also fabricated on the same epitaxial sample. Enhanced device gain, current drive density, breakdown, on/off current ratio, and high-temperature stability up to 450K are also investigated in this work.