Atomic structures of Si(111) 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 degreesC). 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(I 1 1)1 x I partially hydrogenated. At high temperature. the conventional 7 x 7 structure is observed. For intermediate temperatures, a (root3 x root3)R30degrees 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 x 7 and the (root3 x root3)R30degrees structures The (root3 x root3)R30degrees areas slowly transform at the time scale of our experiments into 7 X 7 reconstruction. We discuss the role of hydrogen in the behavior of the growing surface structures. (C) 2002 Elsevier Science B.V. All rights reserved.