Modelling the Cu mono-atomic wire formation on Pt vicinal surfaces using kinetic Monte Carlo simulations

Heteroepitaxial growth of the Cu-Pt system is investigated using kinetic Monte Carlo simulations based on a semi-empirical description of metal-metal interactions to interpret recent experiments devoted to the formation of mono-atomic copper wires on the steps of the vicinal Pt surface. We show that step decoration occurs for the narrow temperature range [250, 300] K in agreement with growth experiments. An exchange mechanism leading to interlayer diffusion at step edges which could strongly influence the temperature range for which the perfect Cu wires are observed is also introduced in our model. In addition, we find that an activation barrier higher than 0.6 eV for this exchange process is necessary to reproduce the experimental features observed by Gambardella et al. We also show that this process, when active, is responsible for a modification of the scaling law governing the island density evolution on the step.