Optical properties of GaSb/Al0.4Ga0.6Sb multiple quantum wells

The optical properties of GaSb/Al0.4Ga0.6Sb multiple quantum well structures grown by molecular beam epitaxy on GaAs substrates were studied through absorption and photoluminescence measurements. Despite the various difficulties in growing good quality GaSb-based heterostructures a clearly resolved splitting between the absorption peaks related to the n = 1 heavy and light hole excitons was observed in the energy range 0.85-1.15 eV even at room temperature. A detailed line shape analysis of the excitonic absorption peaks has been carried out in the GaSb/(AlGa)Sb MQW system: the reliability of such analysis was confirmed by the fact that the experimentally determined ratio between heavy to light "in-plane" reduced masses is in excellent agreement with the ratio in the literature. The energies of the interband electronic transitions, calculated within the envelope function approximation including strain effects, show a discrepancy with experiments interpreted in terms of interfacial roughness. The values of band offset and nonparabolicity coefficients resulting from the analysis are in good agreement with the data reported in the literature.