Dynamics of irreversible island growth during submonolayer epitaxy

The nucleation and growth of two-dimensional islands during the submonolayer stage of epitaxial growth is studied with kinetic Monte Carlo simulations and mean-field rate equations. Previous work on irreversible growth is extended to include relaxation of island shapes by edge diffusion. Island morphologies range from ramified structures at low temperatures to compact, polygonal shapes at higher temperatures. Using a self-consistent calculation of the rate coefficients, quantitative agreement is obtained between the solution to coupled, mean-field rate equations and the simulation results for average quantities. The island size distribution function is described by a single universal ''scaling function.'' The average island size is the only important scale for determining island densities. It is shown that the general form of the scaling ansatz applies to wider range of coverages than anticipated previously. This scaling form is combined with the solution to the rate equations to explore explicitly the D/F dependence of the number density of islands (D is the surface diffusion coefficient and F is the deposition flux)