OPTICAL CHARACTERIZATION OF MOLECULAR-BEAM EPITAXIALLY GROWN INASSB NEARLY LATTICE-MATCHED TO GASB

Molecular beam epitaxially (MBE)-grown InAsSb nearly lattice matched t o (001) GaSb substrates has been studied by infrared absorption, photo luminescence (PL), and double crystal x-ray diffraction (DCXRD). The a bsorption measurements, made at temperatures of 6-295 K, resulted in d eterminations of the temperature and compositional dependencies of the energy gap and the absorption coefficients for InAs1-xSbx (0 less tha n or equal to x less than or equal to 0.192). Temperature- and laser e xcitation power-dependent PL measurements showed only a single band ed ge 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 obse rvations of LO-phonon replicas indicate the good quality of this mater ial. However, careful analysis of the PL data indicates that even this good material may have a tendency for phase separation resulting in c ompositional 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% fo r 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.