Surface morphology of homoepitaxial GaSb films grown on flat and vicinal substrates

We have compared the surface morphology of GaSb homoepitaxial films grown on both flat and I vicinal [miscut towards (111)A] (001) substrates using atomic force microscopy and scanning tunneling microscopy. Mound formation is observed for GaSb homoepitaxy on the flat substrates over a range of growth temperatures when either Sb-2 or Sb-4 is used to supply the group V flux. At sufficiently high growth temperatures, which are different depending on whether Sb-2 or Sb-4 is used, the mounds transform into fairly well-defined pyramids comprised of distinctly stacked layers that are clearly separated by monolayer-height steps. Furthermore, at the tops of the pyramids are sharp, tower-like features that are similar to15Angstrom in height. Mounds also appear during homoepitaxy on the vicinal substrates at lower growth temperatures; however, both mounds and pyramids can be suppressed when using either Sb-2 or Sb-4 by growing at temperatures above similar to400degreesC. We discuss and compare qualitatively the shape of the observed mounds with predictions of evolving morphology based on models of unstable epitaxial growth. (C) 2002 Elsevier Science B.V. All rights reserved.