The structure of thin film which grows on metal surfaces under electrodeposition is studied using a kinetic Monte Carlo method. As a model of crystal growth from solution, we extended the solid-on-solid model so that lattice defects (vacancies) were allowed to form in the film, and performed the simulations for a two-dimensional square lattice model. We take into account adding atoms on and subtracting atoms from the surface, and the diffusion of adatoms on the surface.
The growth rate is controlled by the difference in the chemical potential between the fluid and solid phases. The chemical potential μ corresponds to the overpotential in the electrodeposition. We performed the simulations for a given binding energy between atoms and for several values of μ at a constant temperature. It is shown that surface changes from monolayer to multilayer structures and point defects appear in the film as μ increases. For sufficiently large values of μ, the surface does not show a layer structure and large voids are observed as well as point defects.
The formation process and the structure of defects are closely related to the surface structure.