Two-Dimensional Epitaxial Nucleation with Large Critical-Nucleus Size

A Monte Carlo simulation is carried out for the epitaxial nucleation of two-dimensional islands at low lateral-binding energies, which implies a large value of the critical-nucleus size i. For small normalized incident fluxes, it is shown that (1) the island-size distribution takes on a bimodal shape if the coverage is large enough and (2) the island density is minimum for an island size close to the critical-nucleus size. For large normalized incident fluxes, the island-size distribution is a steadily decreasing function whatever the coverage. It is found that the density of supercritical-size islands is a power function of the normalized incident flux. With increasing i, the index of the function changes until i= 4 and then remains at 2/3.