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HL: Fachverband Halbleiterphysik
HL 44: Poster Session I
HL 44.81: Poster
Tuesday, March 15, 2011, 18:00–21:00, P3
Valence Change of SrTiO3 in a DC Electric Field due to Oxygen Redistribution — •Hartmut Stöcker1, Tilmann Leisegang2, Matthias Zschornak1, Juliane Seibt1, Florian Hanzig1, and Dirk C. Meyer1 — 1TU Bergakademie Freiberg, Institut für Experimentelle Physik, Leipziger Str. 23, 09596 Freiberg — 2Forschungszentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden
Strontium titanate is an oxidic semiconductor and crystallizes in the perovskite-type of structure, however, several methods have been shown to induce distortions of this perfect cubic lattice. One of the key parameters is the oxygen stoichiometry that on the one hand acts as doping and has great influence on the electric conductivity but on the other hand also couples to the crystal structure. Since oxygen ions and vacancies are electrically charged, external electric fields make it possible to redistribute oxygen and to study accompanying structural modifications. Therefore, SrTiO3 (001) wafers have been investigated in situ by fluorescence X-ray absorption near edge structure (XANES) analysis in grazing incidence geometry. The XANES spectra show a clear shift of the Ti-K absorption edge energy depending on the polarity of the applied static electric field. The shift can be attributed to a change of the Ti valence state due to diffusion of oxygen in the near-surface region. No shift was observed for the Sr-K absorption edge energy. A controlled switching of the Ti valance may give rise to a variety of interesting applications.