Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 24: Teilchen und Cluster I

O 24.6: Vortrag

Samstag, 5. März 2005, 16:15–16:30, TU EB301

Tunneling Spectroscopy of large deposited silver clusters on Germanium (001) — •K.-L. Jonas, F. Geisler, J. Bansmann, V. v. Oeynhausen, and K.-H. Meiwes-Broer — Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock

Silver clusters of several nanometer sizes are produced by continuous arc discharge in a hollow cathode design and deposited onto germanium (001). The cluster source is directly attached to a UHV-chamber and provides a high cluster flux of about 6·10⁸ /cm²s. Low temperature tunneling spectroscopy is used to analyse the density of states and the transport via the cluster/interface system, respectively. The clusters are sufficiently fixed at their positions due to the significant silver-germanium interaction when observed by tunneling at over wide parameter range. Transport under the probing tip - known for weakly interacting systems - is suppressed. The spectra observed contain several structures as a dip-like conductance drop to finite but non-zero values at the Fermi level. The dip is discussed in terms of an underlying Schottky contact. Following this idea, the non-zero conductance indicates leak channels in the interface region via silver- germanium bonds. Further, distinct conductance maxima are found. These maxima positions are discussed with respect to one-dimensional quantization of electronic states.