AVS 47th International Symposium
    Surface Science Friday Sessions
       Session SS+MC-FrM

Paper SS+MC-FrM4
Behavior of Lightly Doped-electrons on the Electronic Structure of SrTiO@sub 3@: An Angle-resolved Photoemission Study

Friday, October 6, 2000, 9:20 am, Room 209

Session: Characterization of Oxides and Thin Films
Presenter: Y. Aiura, Electrotechnical Laboratory, Japan
Authors: Y. Aiura, Electrotechnical Laboratory, Japan
H. Bando, Electrotechnical Laboratory, Japan
I. Hase, Electrotechnical Laboratory, Japan
T. Yasue, Tsukuba University, Japan
T. Saitoh, University of Colorado
D.A. Dessau, University of Colorado
Correspondent: Click to Email
Behavior of lightly doped-electrons on the electronic structure of SrTiO@sub 3@ has been studied using angle-resolved photoemission spectroscopy (ARPES). Two states in the band gap region of SrTiO@sub 3@ (in-gap states) are observed; a state with a sharp Fermi cut-off (metallic state) and a broad state centered at ~1.5eV below the Fermi level (~1.5eV state). In order to study the origin of the metallic state, we have calculated the energy-band of non-doped (stoichiometric) SrTiO@sub 3@ and lightly electron-doped SrTiO@sub 3@ based on the full-potential linearized augmented plane wave (FLAPW) method. From comparison between the calculated results and the experimental ones from ARPES, it was shown that the metallic state can be quite well explained by the rigid-band behavior based on one-electron band theory. For the ~1.5eV state, on the other hand, ARPES spectra showed that there is no visible empirical energy dispersion and that its spectral intensity is very sensitive to the surface condition. These experimental results means that the ~1.5eV state is not caused by the bulk electronic structure, but the surface one due to the surface defects.