Surface electromigration of metal atoms on Si(111) surfaces studied by UHV reflection electron microscopy

Abstract

Surface electromigration of metal atoms on Si(111) surfaces, reported previously by reflection high energy electron diffraction and Auger electron microscopy, is studied by ultra-high-vacuum reflection electron microscopy (REM). Au and In are deposited in the form of a stripe on clean Si(111)7 × 7 surfaces, and movement of the stripe edges and changes of surface structures due to surface electromigration are in-situ observed when a current is fed through the Si crystal perpendicularly to the stripe. In the case of Au deposit, migration to the anode is observed and structure changes from the 7 × 7 to Si(111)5 × 1-Au structures are noted on the surface between the stripe and the anode. The shapes of the surface atomic steps change during the transition. The cathode side edge of the stripe is noted to move slowly to the anode. The migration not only on adsorbed layers but also on clean Si(111) surfaces is noted. In the case of In, electromigration to the cathode is observed. Changes of the structure from the 7 × 7 to Si(111)4 × 1-In structures are noted in the area between the stripe and the cathode. The step shapes do not change during the transition.