Study of p-GaN Gate MOS-HEMT with Al₂O₃ Insulator for High-Power Applications

In this work, an enhancement-mode (E-mode) p-GaN gate metal–oxide–semiconductor high-electron-mobility transistor (MOS-HEMT) with 10-nm-thick Al₂O₃ film was successfully fabricated. Good oxide film quality and excellent Al₂O₃/p-GaN MOS interface properties were achieved, as evidenced by the C–V curves and hysteresis effect of Al₂O₃/p-GaN metal–oxide–semiconductor capacitors (MOSCAPs). Compared to the p-GaN gate, the HEMT exhibited threshold voltage (V_th) of 1.5 V and maximum drain current (I_D,max) of 189 mA/mm, the p-GaN gate MOS-HEMT with dielectric oxide Al₂O₃ exhibited higher threshold voltage of 2.1 V, and comparable maximum drain current of 217 mA/mm. In addition, owing to the high-energy bandgap and high breakdown field of Al₂O₃, the p-GaN gate MOS-HEMT demonstrated lower gate leakage current and higher breakdown voltage. The results indicated that p-GaN gate MOS-HEMT with Al₂O₃ gate insulator was promising for high-power application.