Time-resolved spectra and kinetics of the exciton photoluminescence in different types of GaAs/AlAs superlattices

The temperature dependence of the recombination dynamics of excitons is investigated by time-resolved photoluminescence spectroscopy in (GaAs)(n)/(AlAs)(n) superlattices, where n denotes the layer thickness in monolayers, for different types of band structures. In direct-gap superlattices with a layer thickness of the order or larger than the exciton Bohr radius, the carrier dynamics is dominated by the transfer from light-hole to heavy-hole excitons. When the layer thickness becomes smaller than the exciton radius, the dynamics of free excitons is controlled by localization. vb In quasi-direct and indirect-gap superlattices, the influence of lateral potential fluctuations due to interface roughness completely governs exciton recombination. (C) 2000 Academic Press.