Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 21: Poster IB (Oxide semiconductors; II-VI and group IV semiconductors; Nanotubes and Buckyballs)
HL 21.15: Poster
Montag, 16. März 2015, 15:00–20:00, Poster B
LEEM and XPEEM studies of MgO films on Ag(100) — •Sabrina Pechmann1, Gina Peschel2, Hagen W Klemm2, Thomas Schmidt2, and Rainer H Fink1 — 1Physical Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Germany — 2Chemical Physics, Fritz Haber Institute of the Max Planck Society Berlin, Germany
Metal oxide thin films on metal supports are important for various technological applications like catalysis or the fabrication of electronic devices. Therefore, it is necessary to understand the electronic properties of the interfaces, as well as microscopic structure and morphology of the films. Especially MgO on Ag(100) serves as an attractive model system as the lattice mismatch between both bulk structures is only 3.1%, allowing epitaxial growth with just a small number of grain boundaries. Nevertheless, defects like non-stoichiometries, or vacancies influence the surface properties of the oxide layer to a large extend. Exposure to X-rays and even low-energy electrons (up to 200 eV), already leads to the formation of so-called color centers. We investigated the growth and structural properties of epitaxial MgO thin films on Ag(100) by LEEM and XPEEM as both techniques provide insight into structural and chemical sensitivity and directly visualize the influence of surface defects, e.g., step bunches. We could observe a strong influence of low-energy electrons and X-rays on the metal oxide layer, like the reversible formation of long-range ordered oxygen vacancies and even quadrangular structures. First results concerning those effects will be presented.