P-type GaN metal oxide semiconductors (MOS) with ZrO2 dielectrics have been fabricated. Here, H2O and O-3 were selected as oxidizers for ZrO2 growth by atomic layer deposition. The MOS devices with O-3 oxidant demonstrated a smaller flat band voltage than that with H2O oxidant. A Ga2O3 interlayer was formed between GaN and O-3 -grown ZrO2, which can effectively decrease interfacial state density to 1.5 x 10(11) cm(-2). Meanwhile, the innovation of AlZnO (AZO)/Ag nanowires (AgNWs)/AlZnO composite electrodes can further decrease the flat band voltage to about a half compared to that with traditional Cr/Au electrodes and superior electrical performance was achieved.