Modeling of molecular beam epitaxy growth under ehrlich-schwoebel potential barrier effects

Abstract

In molecular beam epitaxy (MBE) film growing, atoms may encounter a step edge - a region where two terraces of different height meet - while diffusing across the growth front. A diffusing atom must overcome an additional potential barrier when hopping down from the upper terrace to the lower one. This barrier is known as the Ehrlich-Schwoebel (ES) barrier. In this work, a discrete MBE model on one-dimensional substrate is used to determine effects of the ES barrier on MBE growth. We found mound formation on the grown surface with larger mound structure in weaker barrier systems and smaller mounds in stronger ones. The study of the time evolution of mound properties such as the average mound radius and the average mound height shows that this growth process can be divided into two stages. In the initial stage, individual mound coarsens resulting in the increase of the mound radius. In the second stage at later time, coarsening process becomes very slowand the mound radius is approximately constant. With mound radius fixed as a constant in time, newly deposited atoms are incorporated on top of existing mounds and the average mound height increases as growth time increases