STRUCTURE AND MORPHOLOGY OF AU GROWN ON AG(110)

We report the results of an experimental investigation using medium-energy ion scattering of the growth of Au on the Ag(110) surface for Au coverages ranging from 0.05 up to 15 monolayers. The lattice parameters of Au and Ag are well matched, and the surface energies of Au and Ag are similar. One would therefore expect a simple growth mode [as earlier observed in the Au/Ag(111) system]. In contrast to this simple picture, we find the growth of Au/Ag(110) to be much more complex with several additional structural phenomena. At low Au coverages, the surface symmetry remains that of the (1 X 1) substrate. In the submonolayer coverage range, we find that Au grows in bilayer units in a Volmer-Weber growth mode. At higher coverages, the surface changes to a (1 X 3) and eventually to a (1 X 2) symmetry. With these changes of symmetry, we find changes in the growth properties such that the Ag surface is completely covered by the Au film in the (1 X 2) phase.