INVESTIGATION OF SB/GASB MULTILAYER STRUCTURES FOR POTENTIAL APPLICATION AS AN INDIRECT NARROW-BANDGAP MATERIAL

In this paper we provide the rationale, and a preliminary experimental investigation of, the Sb/GaSb system as a potential indirect narrow-gap superlattice, where spatial quantization effects are proposed to induce a positive valence-conduction band energy gap in the Sb semimetal layers. The experimental study has investigated growth of Sb/GaSb single heterojunctions and elementary multilayer structures using molecular beam epitaxy. Although Sb is rhombohedral and GaSb has the cubic zinc blende structure, the biatomic planar structure of Sb mimics the (111) plane in the zinc blende structure, and registry between the zinc blende and rhombohedral lattice can be preserved if epitaxy is achieved along the [111] direction. We show that high-quality Sb layers can be grown epitaxially on GaSb[lll] homoepitaxial films, and that GaSb can be subsequently grown on Sb. The epilayer growth and heterojunction structure have been characterized by in situ reflection high-energy electron diffraction, x-ray diffraction and x-ray photoelectron spectroscopy. Electrical properties of Sb epilayers with thicknesses in the range 150-2500 angstrom have been determined by temperature-dependent Hall measurements.