Surface morphology and electronic structure of bulk single crystal β-Ga2O3(100)

Experimental studies of the surface morphology and electronic structure of bulk single crystals of the transparent and wide gap semiconductor gallium oxide $\left(\beta {\text{-Ga}}_2{\text{O}}_3\right)$ have been conducted using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and angle-resolved photoemission spectroscopy (ARPES). Atomically resolved STM and LEED results for the $\beta {\text{-Ga}}_2{\text{O}}_3\left(100\right)$ surface clarify that the predominant surface termination contains both gallium and oxygen, and this surface does not exhibit a reconstruction. The valence band structure was obtained with ARPES and shows good agreement with existing theoretical works at the zone center and along the $a^{\ast }$ and $c^{\ast }$ directions, except that the calculated bandwidth is $\sim 7\%$ too small. There is poorer agreement along the $b^{\ast }$ direction, where the experimental bands disperse more strongly than the calculations.