The atomic diffusion of Y atoms on the Si(111)-7x7 surface at room temperature was studied by using a combination of scanning tunneling microscopy and kinetic Monte Carlo simulations. The experiment provided the occupancy statistics of faulted and unfaulted half-cells by Y atoms. A model taking into account the attractive interactions among adsorbates which provided the best quantitative agreement with the experimental data by kinetic Monte Carlo simulations was introduced. For low Y coverages, single Y adatoms as well as clusters could be identified inside the 7x7 reconstruction half-cells in the scanning tunneling microscopy images. Single Y adatoms were highly mobile inside the halves, resulting in a characteristic fuzzy appearance of the half-cell. The Y adatoms as well as the clusters present strong electronic effects, which provided information concerning their interaction with the substrate Si atoms.

Diffusion and Nucleation of Yttrium Atoms on Si(111)7x7 - a Growth Model. C.Polop, E.Vasco, J.A.Martín-Gago, J.L.Sacedón: Physical Review B, 2002, 66[8], 085324 (7pp)