Electronic structures and optical properties of Si- and Sn-doped <i>β</i> -Ga ₂ O ₃ : A GGA+ <i>U</i> study

Abstract

The electronic structures and optical properties of β -Ga 2 O 3 and Si- and Sn-doped β -Ga 2 O 3 are studied using the GGA + U method based on density functional theory. The calculated bandgap and Ga 3d-state peak of β -Ga 2 O 3 are in good agreement with experimental results. Si- and Sn-doped β -Ga 2 O 3 tend to form under O-poor conditions, and the formation energy of Si-doped β -Ga 2 O 3 is larger than that of Sn-doped β -Ga 2 O 3 because of the large bond length variation between Ga–O and Si–O. Si- and Sn-doped β -Ga 2 O 3 have wider optical gaps than β -Ga 2 O 3 , due to the Burstein–Moss effect and the bandgap renormalization effect. Si-doped β -Ga 2 O 3 shows better electron conductivity and a higher optical absorption edge than Sn-doped β -Ga 2 O 3 , so Si is more suitable as a dopant of n-type β -Ga 2 O 3 , which can be applied in deep-UV photoelectric devices.