The effect of island coalescence on island density during epitaxial growth

The effect of island coalescence on island density during epitaxial growth is studied by kinetic Monte Carlo simulations. We find that the ratio N/N-c between the island density N at time t and the number N-c of islands per unit area that have coalesced up to the time t is a function of the coverage, but is independent of the specific material or the growth conditions. We analyze the results of our simulations by using several mean-field kinetic models of increasing complexity. They show that the simulation results are reproduced accurately only by a kinetic model which includes the spatial correlation between the location of the islands. The existence of a denuded zone around each island is particularly important, as it pushes the onset of coalescence towards higher coverages and increases the coalescence rate when the process starts. (C) 1997 Elsevier Science B.V.