Molecular-dynamics description of early film deposition of Au on Ag(110)

Abstract

We simulate the vapor deposition of the first three monolayers (ML) of Au on Ag(110) using surface-embedded-atom potentials fit to both the bulk and surface properties of the low-index faces of the Au and Ag single crystals. The simulation is carried out with the molecular-dynamics code damsel using the technique of computational annealing to mimic room-temperature deposition. We find that up to 1 ML most of the Au atoms interdiffuse to the substrate layer with little three-dimensional growth to that point. Subsequently the growth becomes more three-dimensional resembling a 3×1 missing-row reconstruction, with the top layers containing higher proportions of Au atoms. The simulations thus support the interdiffusion of a single layer of Au below the Ag surface and a Stranski-Krastanov (SK) growth mode consistent with recent scanning-tunneling-microscopy (STM) analyses. We examine the dynamic mechanisms of the deposition and find that atomic replacement and high Ag mobility largely account for the observed growth. Comparisons are carried out with previous analyses of medium-energy ion-scattering and STM experiments with agreement on the interdiffusive SK growth mode interpretation.