Energy relaxation processes of hot quasi-two-dimensional excitons in very thin GaAs/AlGaAs quantum wells by exciton–acoustic-phonon interaction

The rising time of the excitonic luminescence in GaAs/AlGaAs quantum wells is studied as a function of the well width. For well thickness below approximately 20 Å, we find an increase of rising time with decreasing well width. We explain the dependence of the rising time on well width in very thin quantum wells by the slow-down energy relaxation and/or exciton migration processes due to the decrease of the scattering rate of the exciton–acoustic-phonon interaction.