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-Ga2O3 can be improved by doping Sn. The calculation results are consistent with experimental results which have been reported.