Effects of post-annealing temperature and oxygen concentration during sputtering on the structural and optical properties of β-Ga2O3 films

In this study, β-Ga2O3 thin films were directly deposited on sapphire substrates by radio-frequency magnetron sputtering. The effects of post-annealing temperature and oxygen concentration during sputtering on the structural and optical properties of the films were investigated in detail. The results indicated that the crystalline quality of the films improved with increasing post-annealing temperature. When 1 vol. % oxygen was included in the deposition process, β-Ga2O3 film displayed the best crystalline quality, the band gap and atomic ratios of O to Ga of the film were increased, and the content of oxygen vacancies in the film was effectively lowered. These results revealed an effective, convenient method to prepare high-quality β-Ga2O3 thin films.