AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors using oxide insulator grown by photoelectrochemical oxidation method

A photoelectrochemical oxidation met hod was used to directly grow oxide layer on AlGaN surface. The annealed oxide layer exhibited beta-Ga2O3 and alpha-Al2O3 crystalline phases. Using a photoassisted capacitance-voltage method, a low average interface-state density of 5.1 x 10(11) cm(-2) . eV(-1) was 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 V-GS = 10 V and reverse gate bias of V-GS = -10 V, respectively. The maximum value of g(m) is 50 mS/mm of V-GS biased at -2.09 V.