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DS: Fachverband Dünne Schichten
DS 9: Thin Film Characterisation: Structure Analysis and Composition (XRD, TEM, XPS, SIMS, RBS, ...) II
DS 9.2: Vortrag
Montag, 14. März 2011, 12:15–12:30, GER 38
Structure of heteroepitaxial type-B oriented CeO2(111) on cubic- and hexagonal-Pr2O3/Si(111) supports — •Marvin Zoellner1, Joachim Wollschläger2, Marcus Bäumer3, Michael Reichling2, Peter Zaumseil1, and Thomas Schroeder1 — 1IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany. — 2Universität Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany. — 3Universität Bremen, Leobener Str. 2, 28359 Bremen, Germany.
Single crystalline epitaxial cerium oxide is of interest for model catalysis. Furthermore, a combination with praseodymium oxide exhibits an enhanced oxygen storage capability. Therefore, CeO2(111) thin films were grown on cub-Pr2O3(111)/Si(111) and hex-Pr2O3(0001)/Si(111) by molecular beam epitaxy (MBE). The cub-CeO2(111) lattice has an ABCABC... and the hex-Pr2O3(0001) lattice an ABABAB... stacking sequence. In such oxide heterostructures stacking twins can occur, which influence catalytic activity. Reflection high energy electron diffraction (RHEED) was used for in-situ monitoring of the layer orientation. To gain a global and local insight of the heterostructures, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were performed ex-situ. Finally, synchrotron radiation-grazing incidence X-ray diffraction (SR-GIXRD) gives a surface sensitive twin analysis. A twin-free, exclusively type-B oriented CeO2[1-10]||Si[-110] epitaxial relationship of the CeO2(111) film on the cub- as well as on the hex-Pr2O3 was detected. Theoretical ab initio calculations were carried out to gain an understanding of the unexpected twin-free growth mechanism.