  The theoretical and experimental status of surfactant mediated semiconductor
epitaxial growth is reviewed. We discuss homoepitaxy as well as heteroepitaxy,
and emphasize in particular issues related to the mechanism by which
surfactants suppress growth of three dimensional islands in heteroepitaxy. We
argue that the dominant mechanism is passivation of island edges, which leads
to suppression of attachment and detachment of atoms to and from island edges.
