Atomic structures of Si(1 1 1) surface during silane UHV-CVD

Si(1 1 1) homoepitaxy using silane in ultra-high vacuum chemical vapor deposition conditions has been studied with scanning tunneling microscopy during growth at high temperatures (460–560 °C). We have especially been interested in the atomic structure of the growing surface. This latter exhibits different structures as a function of growth temperature. For low temperature, there appears a disordered phase which corresponds to the migration of SiH species on Si(1 1 1)1×1 partially hydrogenated. At high temperature, the conventional 7×7 structure is observed. For intermediate temperatures, a (√3×√3)R30° structure covers the surface. The surface structures have also been studied during annealing at the growth temperature. The disordered phase is rapidly converted into the 7×7 and the (√3×√3)R30° structures. The (√3×√3)R30° areas slowly transform at the time scale of our experiments into 7×7 reconstruction. We discuss the role of hydrogen in the behavior of the growing surface structures.