The 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 Y occupancy statistics for faulted and unfaulted half-cells. A model which took account of the attractive interactions among adsorbates and which provided the best quantitative agreement with experimental data using kinetic Monte Carlo simulation was introduced. For low Y coverages, single Y adatoms as well as clusters could be identified inside the 7x7 reconstruction half-cells using scanning tunneling microscopy. Single Y adatoms were highly mobile within the halves, resulting in a characteristic fuzzy appearance of the half-cell. The Y adatoms, as well as the clusters, exhibited marked electronic effects which furnished information concerning their interactions 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], 853241