Optical characterization of molecular beam epitaxially grown InAsSb nearly lattice matched to GaSb

Molecular beam epitaxially (MBE)-grown InAsSb nearly lattice matched to (001) GaSb substrates has been studied by infrared absorption, photoluminescence (PL), and double crystal x-ray diffraction (DCXRD). The absorption measurements, made at temperatures of 6-295 K, resulted in determinations of the temperature and compositional dependencies of the energy gap and the absorption coefficients for InAs1-xSbx (0 less than or equal to x less than or equal to 0.192). Temperature- and laser excitation power-dependent PL measurements showed only a single band edge peak for the ternary samples (Delta a/a less than or equal to+0.623%). Both low temperature PL linewidths las narrow as 4.3 meV) and observations of LO-phonon replicas indicate the good quality of this material. However, careful analysis of the PL data indicates that even this good material may have a tendency for phase separation resulting in compositional inhomogeneity as reported previously for MBE-grown InAsSb. (004) DCXRD measurements resulted in lattice mismatches between - 0.629% less than or equal to Delta a/a less than or equal to + 0.708% for these samples, while (115) DCXRD measurements indicated that tensile strain persisted in the epilayers, even for thicknesses up to 1.4 mu m. (C) 1998 American Institute of Physics.