Reflection electron microscopy was used to study the drift velocity of positive monolayer islands on Si(111) under near equilibrium conditions and direct-current heating, and the difference between the velocity of monatomic steps heated by direct current in the step-up and step-down direction under free sublimation. The results obtained at around 1200C showed that the islands move in the opposite direction of the dc and the step velocity for ascending steps with respect to the dc direction was smaller than the velocity for opposite steps with the same inter-step distance. These two experimental results were a clear qualitative prove of the existence of an Ehrlich-Schwoebel effect on Si(111). The experimental results for the step dynamics were analyzed within a modified Burton, Cabrera, and Frank model. It was found that a quantitative agreement between the model and the experimental results needs an enhanced effect of the electric field on the diffusion species.

Experimental Evidence for an Ehrlich-Schwoebel Effect on Si(111). A.Saúl, J.J.Métois, A.Ranguis: Physical Review B, 2002, 65[7], 075409 (9pp)