Photoluminescence from exciton-electron inelastic scattering in a GaAs/AlAs multiple-quantum-well structure

We have investigated the characteristics of photoluminescence (PL) from exciton-electron inelastic scattering in a GaAs (5.1 nm)/AlAs (5.1 nm) multiple-quantum-well structure. The excitation power dependence of PL spectra was measured in a wide temperature region from 10 to 285 K. We detected a PL band which appears with a threshold-like nature at each temperature. In a low temperature region below similar to 80 K, the energy spacing between the threshold-like appearance PL band and heavy-hole exciton almost agrees with the exciton binding energy. This indicates that the PL band originates from well-known exciton-exciton inelastic scattering. In contrast, in a high temperature region above similar to 90 K, the energy spacing continuously increases with an increase in temperature. The temperature dependence of the energy spacing is explained by a theoretical model for exciton-electron inelastic scattering considering energy and momentum conservation in the scattering process. Thus, it is concluded that the mechanism of the threshold-like appearance PL band related to exciton inelastic scattering changes with temperature. In addition, we confirmed that the exciton-electron inelastic scattering produces an optical gain using a variable stripe length method for PL measurements. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim