Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 10: Semiconductor Substrates: Epitaxy and Growth
O 10.2: Vortrag
Montag, 25. Februar 2008, 13:30–13:45, MA 042
Morphological and chemical characterization of thin heteroepitaxial Praseodymium sesquioxide films on Si(111) — •Andreas Schaefer1, Volkmar Zielasek1, Thomas Schmidt2, Anders Sandell3, Joachim Wollschläger4, Jens Falta2, and Marcus Bäumer1 — 1Institut für Angewandte und Physikalische Chemie, Universität Bremen — 2Institut für Festkörperphysik, Universität Bremen — 3Department of Physics, University of Uppsala — 4Fachbereich Physik, Universität Osnabrück
Among the rare earths Praseodymium oxides possess the highest oxygen mobility and a high oxygen storage capability. Due to this fact they are promising candidates for catalytic applications exploiting the variable valency of Pr. A simplified two dimensional model system of the oxide catalyst can be prepared on silicon substrates in an UHV environment to study the atomic details of oxygen transport and transfer when exposed to adsorbed molecules. Here we report on the growth and morphology of heteroepitaxial Pr2O3 films at a low deposition rate on Si(111) which were investigated using Spot Profile Analysis of Low- Energy Electron Diffraction. In the initial stages of growth the specular diffraction spot exhibits a pronounced threefold symmetry most likely reflecting the formation of highly ordered islands of triangular shape as shown by STM. A roughening of the substrate surface is observed during growth of the initial Praseodymium oxide layer. Beyond these morphological studies, preliminary results of a first chemical characterization of the films with and without adsorbates (CO and oxygen) by XAS and XPS will be presented.