Nucleation with a critical cluster size of zero: Submonolayer Fe inclusions in Cu(100)

A single-atom nucleation model is studied in which monomers randomly and irreversibly react with the substrate to become immobile and act as growth nuclei. The reaction kinetics, of first order in monomer density, yields a cluster size distribution that is insensitive to deposition rate and is a decreasing function of cluster size. This matches the experimental behavior of submonolayer Fe inclusions formed by deposition onto room-temperature Cu(100) and observed with the scanning tunneling microscope. © 1994 The American Physical Society.