VACANCY GENERATION AT STEPS AND THE KINETICS OF SURFACE ALLOY FORMATION

The role of step fluctuations in surface reactions is explored. Activa tion energies for various processes relevant to the production of vaca ncies at steps on the Cu(100) surface are calculated in the second-mom ent approximation of the tight-binding scheme. Productions rates for v acancies are calculated analytically and by means of Monte Carlo simul ations. For the specific system of manganese incorporation into the Cu (100) surface, it is shown that manganese is effectively incorporated at step edges due to the step fluctuations. The migration of the incor porated manganese away from the steps is mediated by the vacancies pro duced at the steps. Comparison to recent experimental results on the i ncorporation pattern on differently oriented steps suggests that excha nge processes at steps may also play a role in surface alloy formation .