Bandgap and composition of bulk InAsSbBi grown by molecular beam epitaxy

Abstract

The structural and optical properties of pseudomorphic InAsSbBi grown on GaSb are examined using reflection high-energy electron diffraction, X-ray diffraction, Rutherford backscattering spectrometry, and spectroscopic ellipsometry. The layer studied is 210 nm thick and was grown by molecular beam epitaxy at 280 °C under a (2 × 3) surface reconstruction using near-stoichiometric fluxes. The material is homogeneous and single crystal with no observable defects or surface Bi droplets. The group-V mole fractions are determined using Rutherford backscattering measurements of the Bi mole fraction and X-ray diffraction measurements of the lattice tetragonal distortion. The bandgap energy is determined from the room temperature optical constants measured using spectroscopic ellipsometry. These and measurements from pseudomorphic InAsSb and InAsBi on GaSb are utilized to describe the bandgap energy of InAsSbBi as a function of mole fraction using a bandgap bowing model.