Atomically controlled surfaces with step and terrace of β-Ga2O3 single crystal substrates for thin film growth

The surface of β-Ga2O3 (1 0 0) single crystal grown with floating zone method was treated by chemical–mechanical-polishing (CMP) for 30–120 min followed by annealing in oxygen atmosphere at temperature 600–1100 °C for 3–6 h. The evolution of the step arrangement was investigated with reflection high energy electron diffraction and atomic force microscopy. Atomically smooth surfaces with atomic step and terrace structure of β-Ga2O3 substrates were successfully obtained after just CMP treatment as well as CMP treatment and post annealing at 1100 °C for 3 h. The uniform step height was 0.57 nm, and smooth terrace width was 100 nm, where the misorientation angle was about 0.36°. The obtained atomically smooth surface provides a potential application for the high-quality epitaxial film growth.