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O: Oberflächenphysik

O 34: Teilchen und Cluster (II)

O 34.5: Vortrag

Donnerstag, 29. März 2001, 16:30–16:45, K

Scanning probe imaging of thin Au₅₅ layers at variable temperatures — •G. Radu, U. Memmert, and U. Hartmann — Institut für Experimentalphysik, Universität Saarbrücken, Im Stadtwald, D-66041 Saarbrücken

Ligand-stabilized Au₅₅ clusters are potential building blocks for nanoscale electronic devices. For processing of such devices the kinetics of arranging Au₅₅ clusters on surfaces is of high importance. We present a scanning probe microscopy study of the rearrangement of Au₅₅ layers during heating in ultrahigh vacuum. The clusters were deposited onto mica and HOPG substrates by spin coating from a CH₂ Cl₂ solution. For low enough cluster concentration in the solution the deposit consists of areas with a layer of single cluster height alternating with areas showing the bare substrate. The evolution of this structure was imaged at various temperatures in the range between 300 K and 700 K. Thermally induced rearrangements within the cluster layer were insignificant on mica and mainly tip-induced changes were found. At temperatures above 450 K changes of the layer structures were found which are believed to be related to a thermal decomposition of the ligands. On HOPG the mobility of the clusters is higher and thermal rearrangements of the cluster layer were found for temperatures below 400 K. It is proposed that the difference in mobility is related to the different surface charge for both substrates.