STEP ROUGHENING EFFECT ON ADATOM DIFFUSION

Energy barriers for different movements of a single Cu adatom near ste ps on Cu(001) and Cu(111) surfaces are studied with molecular statics where an embedded-atom potential is used to simulate atomic interactio ns. The effect of step roughening on diffusion over step edges is inve stigated. In these calculations diffusion paths (jump, exchange) with low-energy barriers through kink sites are found. The presence of impe rfections in a step ledge leads to a reduced Ehrlich-Schwoebel barrier in most cases and thus the obtained paths may serve as channels for a datoms to cross the descending steps. The possible consequences of the se findings for growth processes are discussed.