Thermal stability of nitrogen-doped SrTiO3 films: Electronic and optical properties studies

The thermal stability of nitrogen-doped SrTiO3 (001) films in terms of electronic and optical properties has been studied by using x-ray photoemission spectroscopy, x-ray absorption spectroscopy, and spectroscopic ellipsometry techniques. The chemical states of nitrogen in nitrogen-doped SrTiO3 films include both substitutional and interstitial states. The N 2p states localized above the O 2p-derived valence band maximum are attributed to the change of optical properties. Postannealing will induce the valence band edge shift due to the thermal instability of interstitial N states, which may degrade the photocatalysis of nitrogen-doped SrTiO3 films during applications