Study of AlGaAsSb/InGaAsSb strained quantum well grown by molecular beam epitaxy on GaSb(100)

Al0.2Ga0.8As0.02Sb0.98/In0.24Ga0.76As0.05Sb0.95 strained quantum well structures were successfully grown by solid source molecular beam epitaxy. X-Ray rocking curves and reciprocal space mapping were applied to determine the strain status of epilayers. Photoluminescence was used to investigate band alignment of AlGaAsSb/InGaAsSb quantum wells. For samples with low Al concentration barrier, type II band alignment was found in such structures. The optical transition is between bound state in conduction band and continuous state in valence band. If the Al concentration in AlGaAsSb barrier increases, the band alignment changes to type I. The optical transition is between bound states. Due to the 0.5% lattice mismatch between AlGaAsSb layer and GaSb substrate, a thick barrier will lead to relaxation, and this has been proven by PL measurements.