Effect of Post-oxidation Annealing on GaAs Oxides Grown by Liquid Phase Chemical-Enhanced Technique

The characteristics of GaAs native oxides grown by liquid phase chemical-enhanced oxidation technique followed by post-oxidation annealing are investigated. The refractive index of as-grown oxide films increases with increasing As/Ga ratio, which depends on many process factors such as temperature, oxidizing time and pH values of the aqueous solution. Regardless of high or low refractive index as-grown oxide films, their refractive index approaches 1.8 after post-oxidation annealing. A model is proposed to explain this observation. Crystalline β-Ga2O3 is present in the oxide when the oxide is annealed at temperatures above 600°C and when the annealing time exceeds 6h. The shrinkage of oxide film thickness has been found. 30% enhancement of breakdown field strength and an order of magnitude of reduction of leakage current have been also obtained.