Heating-current-induced step motion on Si(111) surface by scanning tunneling microscopy

Abstract

Scanning tunneling microscopy has been made on stepped Si(111) surfaces cleaned by heating at 1200 °C with dc electric current flowing directly through a sample. Heating-current-induced step motion was observed: the step bunching for the current along the step-up direction; the atomic steps with regular spacing for the current along the step-down direction. This step transformation was reversible with respect to the current direction. These results are in good agreement with the recent results by reflection electron microscope [Surf. Sci. 213, 157 (1989)] and could be ascribed to the electromigration effect. On the other hand, the preliminary observation for the dc current flowing perpendicular to the step direction did not show the appreciable step transformation.