Strongly-driven coarsening of height-selected Pb islands on Si(1 1 1)

A theoretical model is proposed to describe the rapid coarsening observed for Pb islands on a Si(1 1 1) surface where classical kinetics breaks down. In this system, quantum size effects produce mesa-like Pb islands with chemical potentials depending strongly on their heights, in addition to the usual dependence on the step curvature. Furthermore, a dense wetting layer enables fast mass transport between islands. Incorporating these features, our theoretical model predicts evolution of the island height distribution in good agreement with experiments.