Analysis of island morphology in a model for Pb-mediated growth of Ge on Si(111)

Analysis of island morphology in a realistic model of surfactant-mediated epitaxial growth is presented and compared with experimental results obtained for Pb-mediated growth of Ge on Si(111). In kinetic Monte Carlo simulations it is found that the clustering of Ge atoms above the surfactant obeys an anomalous scaling, and that the cluster size distribution is self-similar in time, up to the latest stages of coarsening, where Ostwald ripening predominates. The clustering process is limited in time due to the irreversible exchange of Ge atoms with surfactant. Further growth of islands below surfactant leads to their ramification. Islands which do not significantly grow below surfactant are compact, and are characterized by a size distribution whose shape is similar to that obtained within the cluster diffusion model of crystal growth.