Decay process of a crater/hillock and step structure transformation

Abstract

Both the decay process of a crater or a hillock on Si(111) and the step bunching formation accompanying the decay of a periodic array of craters or hillocks on vicinal Si(111) are investigated by using the lattice gas model. We considered two elementary atomic processes, hopping with the Schwoebel effect and evaporation, and carried out the time dependent Monte Carlo simulation. The decay process of a crater or a hillock is caused by the difference of the equilibrium adatom concentrations between at the crater or the hillock edge and at the nearest step edge. The size of a crater or a hillock decreases approximately linearly with time for both kinetics of the diffusion limited and the capture limited. For a periodic array of craters or hillocks on a vicinal surface, the step bunching is formed at the upper side of craters or the lower side of hillocks with the decay of craters or hillocks, in the diffusion-limited kinetics. The evaporation of adatoms accelerates the growth rate of the step bunching and extends the bottom width of craters, reducing the step bunching width.