ELECTRONIC-STRUCTURE OF STOICHIOMETRIC AND REDUCED SRTIO3(100) SURFACES - A PHOTOEMISSION-STUDY

We have performed angle-resolved photoemission and X-ray photoemission studies for stoichiometric and reduced SrTiO3(100) surfaces. In the empirical band structure of the O2p valence bands along the whole DELTA line in the bulk Brillouin zone, there is no essential difference between the stoichiometric and reduced surfaces. Our results are in excellent agreement with the calculation. In addition to the O2p valence band structure, two new states at approximately 1 eV and approximately 11 eV below Fermi level appear for the reduced surface (but not for the stoichiometric surface). We show that both of these states are closely connected with oxygen vacancies near the surface.