DC heating-induced step instability on Si(001) vicinal surfaces

Direct-current (DC) heating-induced step instabilities such as step bunchin g and step wandering on Si(001) vicinal surfaces (0-17 degrees off-angle) w ere studied at 1000-1200 degrees C. It was found that step bunching occurs in the areas where a step-up heating current is supplied. Step wandering oc curs on the vicinal surface inclined towards the [100] direction with a lar ge miscut where a step-down heating current is supplied. The distances betw een neighboring step bands formed on the surfaces after step bunching do no t depend on the off-angle of the initial surfaces. However, the distances o n the surfaces inclined towards the [100] direction are larger than those o n the surfaces inclined towards the [110] direction. They also depend on th e substrate temperature regardless of the off-direction of the vicinal surf aces. These observations indicate that electromigration effects on the (001 ) vicinal surfaces are asymmetric in the mobility of silicon adatoms. (C) 1 999 Elsevier Science B.V. All rights reserved.