First-principles calculations of Ti/N-codoping effect on electronic structures and optical properties of SiO2

The electronic structures and optical properties of varies Ti/N-codoping SiO2 are investigated for the first time using the first principles calculations based on density functional theory (DFT). The results indicate the introduction of doped ions reduce the band gap compared to the SiO2 system, nearly by 1.4 eV on average, which may be partly attributed to the unoccupied N 2p states and the hybridization of Si 3s, 3p with N 2p and 0 2p states. So Ti and N atoms may be possible doped elements for improving the optical properties of SiO2 system.