Diffusion processes of interlayer transport on Ir(111) surfaces were investigated. Hopping and exchange mechanisms were considered at perfect step edges, as well as at step edges with defects. It was found, from molecular dynamics simulations and from explicit calculations of the activation barriers and pre-factors within transition-state theory, that an Ehrlich-Schwöbel barrier of 0.5eV existed for step descent. Overall, the activation barriers and pre-factors were found to be lower for hopping than for exchange at the respective step edges. A detailed analysis was made of where the differences in the pre-factors originated. The most favorable paths for step descent were hopping and exchange at the (100) micro-faceted step edge with one vacancy. Hopping was most probable at low temperatures, while exchange became more favorable at higher temperatures.

Self-Diffusion on Stepped Ir(111) Surfaces. U.Kürpick: Physical Review B, 2004, 69[20], 205410 (6pp)