THE INITIAL-STAGES OF DEPOSITION OF AU AND AG ON CU(001) STUDIED BY LOW-ENERGY ION-SCATTERING

Using impact collision ion scattering spectroscopy, we have studied the initial stage of the deposition of Au and Ag onto the Cu(001) surface. Our analysis provides evidence for surface alloying by the substitution of Cu with Au atoms in the surface, even at very low coverages at room temperature. However, the diffusion of Au atoms into the Cu substrate was not observed at coverages below 0.25 ML. The growth of an hexagonal c(2 x 14)-Au layer on top of the first c(2 x 2) structure was found to promote the diffusion of Au atoms into the Cu substrate, destroying the ordered arrangement of the c(2 x 2) structure. Ag was confirmed to form a simple overlayer up to 1 ML without any diffusion of Ag atoms into the substrate. The growth mode of the Ag deposition was identified to be of the Stranski-Krastanov type.