Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 55: Epitaxie und Oberfl
ächenreaktionen

O 55.1: Vortrag

Mittwoch, 9. März 2005, 10:45–11:00, TU EB107

Surface diffusion and nucleation on Si(111) and Ge(111) 7x7 reconstructed surfaces — •Vasily Cherepanov, Sergey Filimonov, and Bert Voigtländer — Institut für Schichten und Grenzflächen ISG 3, Forschungszentrum Jülich, 52425 Jülich, Germany

Submonolayer deposition on the 7x7 reconstructed Si and Ge surfaces results in formation of two types of objects: the usual 2D islands and small metastable clusters occupying the half unit cells of the surface reconstruction. Using a coarse grain approach we propose a theoretical model with a unified treatment of the coupled system of small clusters and 2D islands. It follows from the model that the densities of 2D islands and small clusters are determined by competition for adatoms. The main energetic parameters determining the measured densities are the diffusion barrier for a single adatom, the energy barrier to reorder the stacking fault unit of the surface reconstruction, and the binding energy of adatoms to the stable small clusters. Simultaneous measurements of the density of 2D islands and the density of small clusters with scanning tunneling microscopy are used to estimate the relevant energetic barriers and to reveal on a quantitative level the influence of the compressive strain, film/substrate material, and surface reconstruction on the island formation and growth.