STEP STRUCTURE TRANSFORMATION-INDUCED BY DC ON VICINAL SI(111)

The step structure transformation between a regular step and a bunchin g structure on Si(111) induced by DC is studied by means of the extend ed BCF (Burton Cabrela Frank) theory, in which surface electromigratio n of Si adatoms is considered. The stability condition of a regular st ep under DC supply is clarified, in addition to that under AC supply. In the unstable condition, the step bunch grows from a small fluctuati on of a regular step. The dynamics of the step structure transformatio n under DC are investigated by solving the kinetic equations on step p ositions at typical temperatures, and the associated bunching mechanis ms are proposed based on the competition among the drift, evaporation and backward diffusion fluxes.