Surface, Step-Edge, and Facet-Edge Diffusion Barriers in Growth of Pb Nanomesas

To obtain a better understanding of the growth kinetics of faceted Pb mesas on Si(111) surface, we perform extensive calculations of diffusion barriers for a Pb adatom (1) on a flat Pb(111) surface, (2) crossing a single A- or B-step edge on the Pb(111) surface, and (3) crossing the joint edge of the Pb(111) and (001) facet, using a modified embedded atom method. We have investigated different diffusion mechanisms mediated by vacancies and concerted displacements of multiple atoms. A quantitative comparison will be made between the calculated results and recent experiments. *This work is supported by NSF.