Study on Preparing β-Ga2O3 Films with Temperature-Controlled Buffer Layer by RF Magnetron Sputtering

β-Ga2O3 thin films were prepared on (0006) sapphire substrates by RF magnetron sputtering. Under the conditions of sputtering power of 80 W, time of 10 min, and total flow rate of 40 sccm in oxygen and argon atmosphere (2.5 % oxygen ratio). Different preparation temperatures were used to conduct layering by temperature modulation. A homogenous β-Ga2O3 buffer layer was grown first, and then the second β-Ga2O3 film was grown on top of it. When the stratified sputtering of different temperature combinations was completed, high-temperature thermal annealing with the same parameters was performed. The effects on the structure, surface morphology, and optical properties of β-Ga2O3 thin films were compared and analyzed when using the preparation sequence of the homogenous buffer layer and the top layer at different temperatures after annealing. Finally, based on the stratified preparation temperature parameters, the optimal stratified temperature parameters were summarized.