Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Engineering Physics

First Advisor

Robert L. Hengehold, PhD


The material parameters and crystalline quality of undoped, MBE-grown InAs1-xSbx nearly lattice-matched to (100) GaSb (-0.617% ≤ Δ a-a ≤ +0.708%) similar to material used for mid-infrared semiconductor lasers were determined by optical characterization. Absorption measurements at temperatures between 6-295 K determined the energy gap and wavelength-dependent absorption coefficient for each sample. The compositional dependence of the energy gap was anomalous when compared to previously reported data, suggesting phase separation existed in the material. The samples were also studied by temperature- and excitation-dependent photoluminescence (PL), which, for the majority of cases, showed only a single band-edge peak, identified by comparison with the absorption data. PL linewidths as narrow as 4.3 meV and LO-phonon replicas indicated high material quality, but the shift of the PL peak to higher energies with increased excitation was greater than expected from band filling alone, and underscored the likelihood of phase separation. Extrinsic PL peaks were also observed from one undoped sample, and identified a F-B transition at 4-7 meV and a DAP transition at 10-14 meV below the band edge. Characterization of InAs1-xSbx:Be identified the Be acceptor energy as >30 meV above the valence band.

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