Effect of nitrogen doping on optical properties and electronic structures of SrTiO3 films

The nitrogen-doping induced changes in optical properties and electronic structures of SrTiO3 films have been investigated by using spectroscopic ellipsometry and x-ray photoemission spectroscopy. Combined with the first-principles calculations, it is found that the localized N 2p states above O 2p states are attributed to the new absorption edge at 500 nm and the photoactivity in the visible light region. Our results are consistent with both recent experimental and theoretical studies on nitrogen-doped TiO2, where the visible light responses arise from the localized N 2p states slightly above the valence-band edge rather than the band gap narrowing. (c) 2006 American Institute of Physics.