Annealing temperature dependence on the electronic structure of the reduced SrTiO3 (111) surface

The electronic structure of the reduced SrTiO3 (111) surface prepared by annealing, in ultrahigh vacuum has been studied using photoemission spectroscopy. In the photoemission spectrum of the reduced surface after annealing at 800 degrees C, a metallic state with a sharp Fermi cut-off is observed in the band gap region. For the reduced surface prepared by annealing at 1200 degrees C, on the other hand, the metallic state becomes drastically weak and a localized state centered at similar to 1.1 eV below the Fermi level is observed in the band gap region. Based on the low energy electron diffraction results, we will discuss the relationship between the spectral feature of these band gap states and the surface geometric structure. (C) 1998 Elsevier Science B.V.