A Monte Carlo simulation of submonolayer homoepitaxial growth on Ag(110) and Cu(110)

Abstract

The low-coverage ( θ≤0.05) growth of Ag/Ag(110) and Cu/Cu(110) is studied by kinetic Monte Carlo simulations. Our model includes deposition, diffusion and fully reversible aggregation on a 2D rectangular lattice with both anisotropic diffusion barriers and anisotropic attachment. The barriers for the diffusion processes are calculated by many-body RGL potentials, and compared to the available data with good agreement. Depending on T, in both metals the model shows morphology transitions to 1D in-channel strips and then to 2D compact islands. The latter transition is due to the activation of in-channel detachment followed by terrace-mediated reshaping and not to direct corner rounding. Even if the transition takes place in the same temperature range for both metals, the 1D strips obtained in Cu are much longer. At the transition, a break in the slope of the island density versus 1/ T is obtained, due to the onset of ripening during growth. There, the island density presents a maximum at very low coverages, followed by a decrease due to island dissolution and not to coalescence. The possibility of extracting the diffusion barriers by measuring the island density is discussed, finding that it is possible to extract a reliable value for the in-channel diffusion barrier in Ag, where the diffusion anisotropy is stronger. In Cu, an average between the in-channel and the cross-channel barriers is extracted.