We have studied effects of surface oxygen vacancies on electronic states of TiO2(110), TiO2(001) and SrTiO3(001) surfaces by means of angle-resolved photoemission spectroscopy. The surface oxygen vacancy induces a state at ∼1 eV below the Fermi level in the bulk band gap. In the angle-resolved photoemission spectra, this state has slight energy dispersion and doesn't cross the Fermi level when the emission angle is changed. These results indicate that the state induced by surface oxygen vacancies is not simply interpreted by delocalized model, and that the localized behavior also plays an important role for the metal-insulator transition of these materials.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering