Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.81: Poster

Dienstag, 15. März 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.