Electronic structure and optical properties of Ge-and F-doped α -Ga₂O₃: First-principles investigations

The prospect of α -Ga₂O₃ in optical and electrical devices application is fascinating. In order to obtain better performance, Ge and F elements with similar electronegativity and atomic size are selected as dopants. Based on density functional theory (DFT), we systematically research the electronic structure and optical properties of doped α -Ga₂O₃ by GGA+U calculation method. The results show that Ge atoms and F atoms are effective n-type dopants. For Ge-doped α -Ga₂O₃, it is probably obtained under O-poor conditions. However, for F-doped α -Ga₂O₃, it is probably obtained under O-rich conditions. The doping system of F element is more stable due to the lower formation energy. In this investigation, it is found that two kinds of doping can reduce the α -Ga₂O₃ band gap and improve the conductivity. What is more, it is observed that the absorption edge after doping has a blue shift and causes certain absorption effect on the visible region. Through the whole scale of comparison, Ge doping is more suitable for the application of transmittance materials, yet F doping is more appropriate for the application of deep ultraviolet devices. We expect that our research can provide guidance and reference for preparation of α -Ga₂O₃ thin films and photoelectric devices.