Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 4: Epitaxie und Wachstum I

O 4.3: Vortrag

Freitag, 4. März 2005, 11:15–11:30, TU EB202

Morphology and structure of pseudomorphic Ni-films grown on the Ir(100)-(1x1) surface — •Bernd Gumler, Andreas Schmidt, Andreas Klein, Lutz Hammer und Klaus Heinz — Lehrstuhl für Festkörperphysik, Universität Erlangen - Nürnberg, Staudtstr. 7, D-91058 Erlangen

Recent investigations of the epitaxial growth of Ni on the hexagonally reconstructed (100) surface of iridium, Ir(100)-(5x1)-hex, have shown that the reconstruction is lifted at very low Ni coverage leading to strong intermixing at the interface resulting in a rather limited order of the film. Therefore we used the surface’s 1x1-structure, which can be prepared as metastable phase, as a template instead of the reconstructed phase. Scanning tunnelling microscopy (STM) and (quantitative) low-energy electron diffraction (LEED) were applied in the investigation. The Ni-Ir epitaxial misfit is as large as 8.2% so that layer-by-layer growth should not be expected. Indeed, we did not succeed to prepare a perfectly flat and closed 2 monolayers film. Surprisingly, yet, deposition of a third Ni layer yielded an almost ideal 3 layers film, i.e. the system seems to return to layer-by-layer growth. In fact, also the 4th layer grows accordingly. The films structures were determined and verified by excellent LEED theory-experiment fits. Structures were found to be tetragonally distorted with layer spacings of about 1.55 Å which are very close to the prediction of elastic theory. The structural influence of hydrogen adsorption on the films was investigated, too.