Investigations of AlGaN/AlN/GaN MOS-HEMTs on Si Substrate by Ozone Water Oxidation Method

Al_0.3Ga_0.7N/AlN/GaN metal-oxide-semiconductor high electron mobility transistors (HEMTs) grown on Si substrates by using ozone water oxidation method are investigated. Superior improvements of 52.2% in two-terminal gate-drain breakdown voltage (BV_GD), 30.3% in drain-source current density (I_DS) at V_GS = 0 V (I_DSS0), 43.6% in maximum I_DS (I_DS,max), 34.7% in maximum extrinsic transconductance (gm,max), and 52.7%/34.3% in unity-gain cutoff/maximum oscillation frequency (fT/f_max) are achieved as compared with a reference Schottky-gated HEMT. Thermal stability is studied by conducting temperature-dependent characterizations of devices at ambient temperatures of 300-550 K. Time-dependent electrical reliability analyses for the devices stressed in off-state (V_GS = -20 V and V_DS = 0 V) for 0-60 h and on-state (V_GS = 2 V and V_DS = 20 V) for 0-20 h are also made to physically investigate the dominant degradation mechanisms. Excellent reliability and thermal stability at 300-550 K are achieved by the present design.