Influence of differences in orientational planar density on the growth of Pb on the i-Ag-In-Yb quasicrystal

Metal adsorption upon the 3-fold and 5-fold symmetric surfaces of the i-Ag-In-Yb quasicrystal has led to the observation of unique growth modes. Here, we present a study of the growth of Pb upon the 2-fold i-Ag-In-Yb surface, where the growth mechanism is found to be different from those observed on the other, higher symmetry surfaces of the same system. Initial Pb atoms occupy non-chemically-specific surface sites before forming a row structure. At higher coverages, the Pb atoms form a dense wetting layer before 1D Pb chains of limited size are self-assembled as a second layer. We therefore consider the Pb atoms to exhibit a type of Stranski-Krastanov growth mode. Substrate-adsorbate interaction is favoured in the wetting layer, before adsorbate-adsorbate interaction promotes chain growth. The difference in growth modes upon the three high symmetry surfaces is discussed with respect to their respective atomic densities.