FORMATION AND EQUILIBRATION OF SUBMONOLAYER ISLAND DISTRIBUTIONS IN AG AG(100) HOMOEPITAXY/

We present an analysis both of the nucleation and growth of two-dimens ional (2D) islands or clusters during deposition of Ag on Ag(100) at 2 95 K and of the subsequent postdeposition equilibration of such island distributions at coverages below about 0.25 monolayer. Island formati on during deposition is shown to be effectively irreversible, and the island density and size and separation distributions are characterized using a combination of scanning tunneling microscopy (STM) and high-r esolution low-energy electron diffraction. Postdeposition coarsening o f the adlayer is monitored via STM and is shown to be dominated typica lly by diffusion and subsequent coalescence of large 2D clusters rathe r than by Ostwald ripening. Tailored studies of such coarsening elucid ate both the kinetics and the underlying cluster diffusion process.