It was noted that electromigration had a marked effect upon the morphology of semiconductor surfaces and produced, for example, step-bunching instabilities. In order to explain these phenomena from a microscopic point of view, self-diffusion on (111) Si was studied by means of first-principles calculations. A mechanism was proposed for a diffusion bias that was produced by external electric fields. A competing wind-effect arose from an enhanced surface electron density; due to incomplete melting. The above competition led to 2 transitions, in the surface kinetics, with increasing temperature. This was in agreement with experimental observations.

D.Kandel, E.Kaxiras: Physical Review Letters, 1996, 76[7], 1114-7