AlGaN/GaN Metal–Oxide–Semiconductor High-Electron Mobility Transistors Using Oxide Insulator Grown by Photoelectrochemical Oxidation Method

A photoelectrochemical oxidation method was used to directly grow oxide layer on AlGaN surface. The annealed oxide layer exhibited beta-Ga2O3and alpha-Al2O3crystalline phases. Using a photoassisted capacitance-voltage method, a low average interface-state density of 5.1 times 1011cm-2. eV-1was estimated. The directly grown oxide layer was used as gate insulator for AlGaN/GaN MOS high-electron mobility transistors (MOS-HEMTs). The threshold voltage of MOS-HEMT devices is -5 V. The gate leakage currents are 50 and 2 pA at forward gate bias of VGS = 10 V and reverse gate bias of VGS= -10 V, respectively. The maximum value of gmis 50 mS/mm of VGs biased at -2.09 V.