| An extensive theoretical study of metal nanostructures on semiconductor surfaces has been performed. Physical models are proposed and/or developed to investigate electric, thermodynamic, and kinetic properties of metal nanomesas. A new concept of the "Coulomb sink" is proposed to elucidate the effect of Coulomb charging on coarsening of metal mesas grown on semiconductor surfaces. A cylindrical hard-wall jellium model combined with a general thermodynamic analysis is developed to investigate the quantum size effects (QSE) on metal nanomesa growth. Based on the scanning tunnelling microscopy experimental results, a direct manifestation of QSE on surface diffusion is provided. A theoretical analysis of selectivity of nucleation location for the two-dimensional islands on top of a metal nanomesa is also presented. The classical diffusion and nucleation theory is applied to determine the Ehrlich-Schwoebel barrier. Extensive first-principles calculations are performed to investigate surface free energies, interlayer spacings, surface stresses, and surface diffusion barriers for Pb(111) films as a function of film thickness. All of these quantities are shown to exhibit the QSE-induced oscillation patterns with increasing film thickness. To obtain a better understanding of the growth kinetics of faceted Pb mesas on Si(111) surface, computational simulations using the modified embedded-atom method are performed to investigate different diffusion modes: direct hopping of an adatom on the surface, and the exchange mechanism between an adatorn and the substrate atom(s). |
