Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 4: Epitaxie und Wachstum I

O 4.4: Vortrag

Freitag, 4. März 2005, 11:30–11:45, TU EB202

Nucleation in the presence of adatom insertion: Co / Pt(111) — •Philipp Buluschek, Stefano Rusponi, Mehdi El Ouali, Emmanuel Vargoz, Klaus Kern, and Harald Brune — Institute of the Physics of Nanostructures, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

We used variable temperature STM to study submonolayer nucleation of Co / Pt(111). Our experiments show that insertion of Co adatoms into the topmost layer of the Pt surface sets in at temperatures as low as 180 K. By relieving the tensile stress of the Pt surface, insertion leads to the formation of double partial dislocation lines. These take the shape of three branched stars.

With the insertion and the associated reconstruction, the Co / Pt(111) system makes a transition from homogeneous to heterogeneous nucleation. The behavior of the island density as a function of deposition temperature has been modeled in kinetic Monte-Carlo simulations. We show that the partial dislocations act as repulsive line defects with a diffusion energy barrier E_d > 670 meV. The comparison between simulations and experiment also enables access to the energy barriers for surface diffusion and the density of included adatoms in the surface.