Electronic structures and optical properties of Si- and Sn-doped β-Ga₂O₃: A GGA+U study

The electronic structures and optical properties of β-Ga₂O₃ and Si- and Sn-doped β-Ga₂O₃ are studied using the GGA+U method based on density functional theory. The calculated bandgap and Ga 3d-state peak of β-Ga₂O₃ are in good agreement with experimental results. Si- and Sn-doped β-Ga₂O₃ tend to form under O-poor conditions, and the formation energy of Si-doped β-Ga₂O₃ is larger than that of Sn-doped β-Ga₂O₃ because of the large bond length variation between Ga-O and Si-O. Si- and Sn-doped β-Ga₂O₃ have wider optical gaps than β-Ga₂O₃, due to the Burstein-Moss effect and the bandgap renormalization effect. Si-doped β-Ga₂O₃ shows better electron conductivity and a higher optical absorption edge than Sn-doped β-Ga₂O₃, so Si is more suitable as a dopant of n-type β-Ga₂O₃, which can be applied in deep-UV photoelectric devices.