First-principles study of n-type tin/fluorine co-doped beta-gallium oxides^*

Defect formation energies, electronic structures and optical properties of Sn-doped β-Ga₂O₃, F-doped β-Ga₂O₃, and Sn/F co-doped β-Ga₂O₃ were calculated using the first-principles. The calculated results of the pure and Sn-doped β-Ga₂O₃ using the local-density approximation (LDA) method show that the lattice parameters and electronic structures are in agreement with previous data. The defect formation energies demonstrate that the doped systems are relatively easy to form under O-rich conditions. Sn-doping, F-doping and Sn/F co-doping make β-Ga₂O₃ become an n-type semiconductor. Sn/F co-doping β-Ga₂O₃ has the smallest effective electron mass and the biggest relative electron number, which is expected to possess good conductivity. Sn/F co-doping β-Ga₂O₃ displays an intense absorption in visible light.