TEMPERATURE-DEPENDENCE OF EXCITON LIFETIMES IN GAAS ALXGA1-XAS SINGLEQUANTUM-WELLS/

We report on continuous-wave and time-resolved measurements of the pho toluminescence of good-quality single quantum wells at low temperature s (4-30 K). Luminescence arising from both free and localized excitons is observed and the influence of excitation localization on the photo luminescence decay time is investigated. Resonant pumping at the light -hole exciton transition is found to greatly increase the generation o f free heavy-hole excitons. In this case, the free-exciton lifetime in creases linearly with temperature (10-30 K) and the dependence of the slope on the well thickness is found to be in good quantitative agreem ent with the theoretical model of Andreani et al. [Solid State Commun. 77, 641 (1991)].