Understanding the early stages of growth of Ge on Si(001) from lattice based simulations

Abstract

A modified lattice model is developed to study the growth of Ge on Si(001). In addition to the usual bond energies, surface reconstruction and elastic strain are explicitly taken into account in this study. We introduce an additional rebonding energy for formation of vacancies in the dimer chains. Kinetic Monte Carlo simulations of growth and annealing successfully reproduce several important features in the range of growth from a small fraction of a monolayer to about one monolayer thick. These include the formation of dimer chains, formation and alignment of vacancies in the dimer chains and the peak in the dimer chain length distribution. We carefully analyze separately the role of mismatch strain and surface reconstruction on this behavior. Through this work, we show a significantly simplified, but nevertheless quantitatively accurate model for the early stages of growth of Ge on Si(001).