Theory of the direct force in electromigration

Abstract

The direct force in electromigration is investigated within the linear-response formalism. Expressions derived by Rimbey and Sorbello are shown to simplify considerably. The result is that the direct force can be obtained from the one-particle Green’s function at the Fermi level. Model calculations for hydrogen interstitials in metals indicate that the direct force exerted by the macroscopic electric field on the hydrogen atom may be on the order of 70–90 % of the force exerted by the macroscopic field on a bare proton. These results show some similarity to Landauer’s theory of the carrier-density–modulation effect, and are in contradiction to the theory of Bosvieux and Friedel.