Step roughening effect on adatom diffusion

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