Electromigration theory unified

Abstract

The starting formula of Bosvieux and Friedel for the force on an ion in a metal due to an applied voltage is shown to lead to the same description as the linear-response approach used in the field since its introduction by Kumar and Sorbello. By this electromigration theory has become a unified theory. It follows after accounting for a treacherous trap term, which at first sight seems to be zero. Up to now Bosvieux and Friedel claimed to predict a completely screened direct force, which means that only a wind force would be operative. In addition the amount of screening has been calculated up to second order in the potential of the migrating impurity, using a finite temperature version of the screening term derived by Sham. For a proton in a metal modeled as a jellium the screening appears to be about 15%, which is neither negligible nor reconcilable with the old full-screening point of view.