Dilute Cu nanostructure stabilized by substrate-mediated interactions onCu(111): Kinetic Monte Carlo simulations

Abstract

The homoepitaxial growth of Cu on $\mathrm{Cu}(111)$ is studied by kinetic Monte Carlo simulations at temperature $15\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and at coverage ranging from 0.005 to 0.04 monolayer (ML). It is shown that substrate-mediated interactions between adatoms lead to the formation of dilute nanostructures with an average nearest-neighbor distance a few times longer than an equilibrium adatom-adatom distance. Morphology of the nanostructure depends on coverage and annealing time. At coverage lower than $0.02\phantom{\rule{0.3em}{0ex}}\mathrm{ML}$ short linear chains develop. During annealing the chains evolve into small dilute clusters. At coverage in the range of $0.02--0.04\phantom{\rule{0.3em}{0ex}}\mathrm{ML}$ the Cu adatoms need $10--20\phantom{\rule{0.3em}{0ex}}\mathrm{min}$ to self-organize into dilute islands with local hexagonal structure. The simulation reveals the existence of energetically favorable adsorption sites at the step edge on the $\mathrm{Cu}(111)$ surface that stimulate aggregation of adatoms near the step.