Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 33: Oxides and Insulators: Epitaxy and Growth
O 33.7: Vortrag
Dienstag, 27. März 2007, 17:15–17:30, H41
Growth of One-dimensional Pd Nanowires on the Reduced SnO2(101) Surface — Alexander Urban1, •Bernd Meyer1, Khabibulakh Katsiev2, Matthias Batzill2, and Ulrike Diebold2 — 1Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum — 2Department of Physics, Tulane University, New Orleans, USA
The adhesion of metals on insulating surfaces is usually much weaker than the cohesion within the metal itself. Therefore, in vapor deposition experiments metals do not ‘wet’ most surfaces of insulators, but 3D cluster formation is observed even at very low metal coverage. In a recent STM experiment [1] however, it was observed that Pd, vapor-deposited on the fully reduced SnO2(101) surface, forms one-dimensional islands with a uniform width of one substrate unit cell and a height of one atomic layer. Neighboring islands do not merge, and the length of the nanowires is only limited by the size of the substrate terraces. DFT calculations have been performed to investigate the atomic processes which lead to this, for metal oxide substrates unusual, overlayer growth [1] It is found that the one-dimensional wires are not the thermodynamically most stable structure, but their formation is dominated by kinetic effects. A pronounced one-dimensional diffusion, combined with a strong interaction of Pd with the surface Sn atoms and the lack of stable binding sites at the sides of the nanowires are responsible for the formation of the one-dimensional islands.
[1] K. Katsiev, M. Batzill, U. Diebold, A. Urban, B. Meyer, submitted to Phys. Rev. Lett.