Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 12: Nanostructures at Surfaces II (Wires, Tubes)

O 12.12: Vortrag

Montag, 26. März 2007, 17:00–17:15, H36

Self-Organized growth of highly ordered metal-nanodots on C/W(110) — •Martin Gabl, Clemens Deisl, Norbert Memmel, and Erminald Bertel — Institute of Physical Chemistry, University of Innsbruck, Austria

The growth of Ag nanostructures on W(110) and C/W(110) is studied by LEED and STM. Whereas on clean W(110) and on the R(15x3) surface large Ag islands are formed, on the R(15x12)-C/W(110) surface the growth of Ag nanodots is observed. The R (15x12) carbon structure serves as a stable periodic template with a nanoscale unit mesh of 14Å x 31Å, which is replicated by the Ag nanodots. Most critical for the fabrication of a regular nanostructure array is the perfect preparation of the R(15x12)-C/W template. Interestingly, it forms more readily in the interior of large terraces, while small terraces tend to stay free of carbon. This implies a crucial role of steps in the C budget of the surface, most probably due to step-enhanced diffusion of carbon into the bulk. At optimum silver coverage (0.12 ML) the Ag nanodots show a narrow size distribution with most islands consisting of hexagonally shaped 7-atom clusters. However, clusters of this size are also observed at slightly higher silver coverages, if deposition temperatures around 500K are used. In this case excess silver agglomerates on terraces with a locally reduced carbon coverage. This implies that the 7-atom clusters are particularly stable, defining a *magic island size*. The present work was supported by the Austrian Science Fund (FWF) and the West-Austrian Initiative for Nano-Networking (WINN).