HETERO-ELECTROMIGRATION ON SEMICONDUCTOR SURFACES

A preferential movement of hetero-adatoms on a clean surface of a semiconductor substrate heated by a DC current (referred to as the hetero-electromigration on semiconductor surfaces to distinguish it from the conventional electromigration) has been investigated for a variety of systems with scanning Auger microscopy (SAM). Several SAM observations for Ag/Si(111) are described as the most evident demonstration of the general features of the mass transport. Unpublished data for Al and Ge on Si(111) and Ag on Ge(111) are also demonstrated briefly with a summary of all the systems investigated. The atomic process of the mass transport is explained in terms of single adatoms with a great mobility exclusively on the intermediate adlayer. The observed dependence of the adatom flux on the doping level of the semiconductor substrate favors rather the electric field acting on adatom ions as a driving force than the wind force predominant in the conventional electromigration.