MONATOMIC TO BIATOMIC STEP TRANSITION DURING EPITAXIAL-GROWTH BY STEP FLOW

We consider the transition of a two domain vicinal surface composed of alternating terraces having 1 X 2 and 2 X 1 reconstructions and separated by A and B steps to a single domain, 2 X 1 vicinal surface with biatomic steps. The sticking coefficients for the rougher B steps are greater on either side of the step than the corresponding A step sticking coefficients and this is shown to provide the kinetic mechanism for a transition to a single domain surface even when the diffusion coefficients on the two kinds of terraces are markedly different. We also determine the explicit time dependence for the terrace widths, which is of a trancendental form.