Relationship between adatom-induced surface resistivity and the wind force for adatom electromigration: A layer Korringa-Kohn-Rostoker study

Abstract

An isolated adatom adsorbed onto the surface of a current-carrying metal feels an electromigration wind force and also changes in the resistivity of the surface. Using the jellium model, it is possible to derive a simple relationship between the wind force $F_w$ and change of the surface resistivity, $\Delta {\rho }_s,$ induced by the adatom. This relationship arises because both of these quantities have a common physical origin: the exchange of momentum between the adatom and the carriers impinging upon the surface from the interior of the metal. A layer Korringa-Kohn-Rostoker calculation is used to study the relationship between the electromigration wind force and the surface resistivity induced by an isolated Ag adatom on Ag(111). In contrast to all prior studies of adatom electromigration at surfaces, our approach permits the computation of the wind forces felt by both the adatom and by atoms within the substrate. We show that the presence of the adatom significantly alters the magnitude of the wind force exerted on substrate atoms that are close to the adatom adsorption site. We use this information to study how the momentum transfer occurring at the surface is partitioned among the adatom and the substrate atoms and show how this effect significantly alters the relationship between $F_w$ and $\Delta {\rho }_s$ derived from jellium models of the substrate.