Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)

O 18.75: Poster

Monday, February 25, 2008, 18:30–19:30, Poster F

Mass selected Co clusters in contact with semiconductor surfaces — •Viola v. Oeynhausen, Kristian Sell, Ingo Barke, and Karlheinz Meiwes-Broer — Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock

Metal-semiconductor structures are of substantial technical relevance since Schottky-barrier based devices are fundamental elements of high-speed electronic applications. Metal nanoparticles on semiconductor surfaces can be seen as a model system for such devices. The Scanning Tunneling Microscope (STM) provides insight in transport properties on nanometer scale and at low temperature. Furthermore, it reveals the geometric structure and shape of clusters, an important prerequisite for understanding the detailed electronic and magnetic properties. We produce mass-selected Co clusters with an Arc Cluster Ion Source (ACIS) and deposite them onto Si(111)7x7 and Ge(001) under UHV conditions. These are ideal substrates due to their well-known electronic structure and simple preparation under UHV conditions. They serve as a reference in STS measurements, thus minimizing tip-induced artefacts. Macroscopic Cobalt surfaces show dominant, highly localized d-states near the Fermi level . Such states are proposed to cause interesting effects like Kondo interaction and spin modulation of captured surface state electrons.