Dynamic behavior of Si magic clusters on Si(111) surfaces

In a scanning tunneling microscope (STM) study of Si(111) surfaces from roo m temperature to 600 degrees C, we find a special type of clusters which ar e not only stable with respect to surface diffusion, but are also the funda mental unit in mass transport phenomena, step fluctuations in detachment an d attachment of Si atoms at step edges, and epitaxial growth. Using Arrheni us analysis, we derive path specific hopping rate parameters for these clus ters. A concerted reaction model is proposed to explain the nucleation and growth behavior of Si on Si(111).