Influence of oxidation and annealing temperatures on quality of Ga₂O₃ film grown on GaN

The effects of oxidation and annealing temperatures on thermally oxidized GaN were investigated. GaN wafers were oxidized at 750 °C, 800 °C and 850 °C, respectively, and the electrical characteristics and interface quality of the resulting metal-oxide-semiconductor capacitors were compared. Among the three samples, the sample oxidized at 800 °C presented the best current-voltage characteristics, capacitance-voltage characteristics in accumulation region and smoothest surface morphology because of better thermal stability and quality of oxide grown at this temperature. Moreover, its electrical breakdown field was higher than the other two orders of magnitude. However, if the sample was annealed at a higher temperature of 850 °C, the quality of its oxide was significantly degraded due to the sharply increasing decomposition of both oxide and GaN at higher temperature. Lastly, the higher oxidation temperature of 850 °C gave the best interface quality.