Electronic structure and optical properties of strained GaSb/AlSb quantum wells under uniaxial stress

The electronic and optical-absorption properties of GaSb/AlSb quantum wells are studied within the framework of the multiband envelope-function approach, considering the valence-band offset value that has been recently proposed. The lattice mismatch strongly modifies the valence-subband dispersion, lowering the energy of the heavy-hole states relative to that of the light-hole levels by a reverse effect of the confinement due to the quantum well. The effects of external uniaxial stress on the valence subbands are also considered. The interband optical absorption is calculated for two polarizations of the light and compared with experimental results recently obtained for some quantum wells. A large variation in the optical matrix elements is found as the parallel wave vector varies in the Brillouin zone and confirms the large mixing between the valence bands away from the zone center.