Excitonic relaxation processes in quantum well structures

Excitonic relaxation processes in quantum well structures are reviewed, focusing attention on the localized and the weakly delocalized regimes. In the localized regime, the acoustic phonon-assisted exciton transfer among the localized sites due to the interface roughness plays an important role in determining the energy and phase coherence relaxation at low temperatures. The effect of magnetic field on the exciton localization is also discussed. In the weakly delocalized regime the possible mechanisms of the dephasing relaxation are the acoustic phonon-mediated intra- and inter-subband scattering, the Fano-type resonance between the light hole exciton and the heavy hole exciton continuum and the elastic scattering by the interface roughness. Under the high intensity excitation, the interactions between excitons and free carriers become increasingly important in determining the dephasing relaxation.