First-principles study on electronic structure and optical properties of Sn-doped β-Ga₂O₃

The band structure, density of states, electron density difference, optical properties of the intrinsic β-Ga₂O₃ and different Sn-doped β-Ga₂O₃ were calculated using the first-principles based on density functional theory. We found that the band gap decreases with the Sn doping concentration. The Fermi energy level moves forward to the conduction band and the shallow donor impurity level is introduced into the conduction band bottom of the Sn-doped β-Ga₂O₃. The absorption band edge was slightly blue-shifted for the 3.125 at% Sn-doped β-Ga₂O₃. However, the absorption edge was red-shifted for the 6.25 at% Sn-doped β-Ga₂O₃. The anisotropic optical properties are investigated by means of the complex dielectric function, which are explained by the selection rule of the band-to-band transitions. All the calculation results indicate that the conductivity of β-Ga ₂O₃ can be improved by doping Sn. The calculation results are consistent with experimental results which have been reported.