First-principles calculations for geometrical structures and electronic properties of Si-doped TiO2

We studied the geometrical structures and electronic properties of Si-doped TiO2 using spin-polarized density functional theory calculations. Our results show that the valence band maximum has a little raise in substitutional Si to O-doped TiO2, and the Fermi level is pinned in the conduction band edge, indicating typical n-type characteristic. In substitutional Si to Ti-doped TiO2, the electron transition energy from the valence band to the conduction band has a decrease about 0.25 and 0.2 eV in anatase and rutile TiO2, respectively, which may be responsible for the experimental redshift of optical absorption edge.