Molecular beam epitaxial growth of Sb/GaSb multilayer structures: potential application as a narrow bandgap system

Abstract

We have performed an investigation into the synthesis of Sb/GaSb heterojunctions and multilayered structures grown by molecular beam epitaxy. The study has been motivated by the potential of the system as an indirect narrow-gap superlattice, where spacial quantization effects are proposed to induce a positive valence-conduction band energy gap in the Sb semimetal layers, and the potential to exploit the large characteristic lengths in the Sb layers for the study of size quantization effects. The GaSb/Sb system presents a number of unique features with regard to synthesis of the epitaxial semimetal/semiconductor system. On the (111) plane of the rhombohedral crystal structure of Sb, both the hexagonal symmetry and in-plane lattice parameter allow near perfect registry to the Sb atoms on the (111) plane of the zincblende structure of GaSb. We show that Sb can be grown epitaxially on GaSb on both (111)A and (111)B orientations for growth temperature T s <240° C and that GaSb can subsequently be grown on the Sb epilayers. The successful growth of GaSb at temperatures less than 240°C has been achieved using migration enhanced epitaxy. Epilayer growth of Sb and Sb/GaSb heterojunction structures have been characterized by in situ reflection high energy electron diffraction, X-ray diffraction and X-ray photoelectron spectroscopy.