Insulating gallium oxide layer produced by thermal oxidation of gallium‐polar GaN

Abstract The benefits of dry oxidation of n ‐GaN for the fabrication of metal‐oxide‐semiconductor structures are reported. GaN thin films grown on sapphire by MOCVD were thermally oxidized for 30, 45 and 60 minutes in a pure oxygen atmosphere at 850 °C to produce thin, smooth GaO x layers. The GaN sample oxidized for 30 minutes had the best properties. Its surface roughness (0.595 nm) as measured by atomic force microscopy (AFM) was the lowest. Capacitance‐voltage measurements showed it had the best saturation in accumulation region and the sharpest transition from accumulation to depletion regions. Under gate voltage sweep, capacitance‐voltage hysteresis was completely absent. The interface trap density was minimum (D it = 2.75×10 10 cm –2 eV –1 ) for sample oxidized for 30 mins. These results demonstrate a high quality GaO x layer is beneficial for GaN MOSFETs. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)