Formation of Semi-Insulating Layers on Semiconducting β-Ga2O3 Single Crystals by Thermal Oxidation

Semi-insulating layers (SIL) were formed on the surfaces of nominally undoped β-Ga 2 O 3 (010) single crystals by thermal oxidation. Capacitance–voltage measurement with double Schottky configuration was performed to evaluate the increase in the thickness of the SIL as a function of annealing temperature and time. A SiO 2 layer prepared on the surface prevented the extension of the SIL, indicating that oxygen incorporation from air and successive bulk diffusion dominated the carrier compensation process. The activation energy of oxygen diffusion coefficient was estimated to be 4.1 eV.