Investigation of the silicon concentration effect on Si-doped anatase TiO2 by first-principles calculation

A first-principles calculation based on the density functional theory (DFT) was used to investigate the energetic and electronic properties of Si-doped anatase TiO2 with various silicon concentrations. The theoretical calculations showed that with Si-doping the valence band and conduction band of TiO2 became hybrid ones with large dispersion, which could benefit the mobility of the photo-generated carriers. This result is in agreement with the experimental reports. At lower doping levels, the band gap of Si-doped anatase TiO2 decreases about 0.2 eV. With the increase of silicon concentration, the band gap increases gradually and larger formation energies are required during the synthesis of Si-doped TiO2.