Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 91: Epitaxy and growth: Oxides and insulators
O 91.2: Vortrag
Donnerstag, 17. März 2011, 17:30–17:45, WIL C307
STM, LEED, and XPS study of ultrathin BaTiO3 films on Pt(100): switching film orientation by controlling substrate reconstruction — •Hannes Beyer, Klaus Meinel, Stefan Förster, and Wolf Widdra — Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
Ultrathin BaTiO3 films have been prepared on Pt(100) using either reactive rf magnetron sputtering or MBE. For both cases the deposition has been performed at room temperature. The magnetron operates in an Ar/O2 gas mixture at 3.6×10−3 mbar, whereas MBE is performed in an O2-atmosphere of 1×10− 6 mbar by reactive co-deposition of Ti and BaO. Long-range ordered films are achieved by post-annealing in O2 at 950 K using both methods. XPS reveals bulk-like stoichiometry of the BaTiO3 films. With STM smooth films with unit cell islands are observed for film thickness of 4 ML.
By either preserving or quenching of the quasi-hexagonal surface reconstruction of Pt(100), it is possible to control the BaTiO3 orientation. The films grow by MBE epitaxially either in (111) or (100) orientation, respectively. In contrast, the sputter deposition of BaTiO3 films results in an initially amorphous surface. Upon annealing of the BaTiO3 film a brilliant BaTiO3(100)-(1×1) pattern is observed independent of the prior substrate reconstruction for thicknesses above 2 ML.