Spatially Resolved Spectra, Effective Mobility Edge, and Level Repulsion in Narrow Quantum Wells

Exciton spectra of narrow quantum wells with non-ideal interfaces are determined by the nature of the disorder-localized quantum mechanical eigenstates. We point out that the level statistics of spatially resolved spectra allows an unexpected approach to estimate the size of the quantum mechanical center-of-mass wavefunctions. In photoluminescence, the exciton relaxation has to be considered, too. We present large scale simulations for a model including static interface-related disorder and acoustic phonon scattering. Strong and systematic deviations between calculated photoluminescence excitation spectra and absorption are found. A sharp drop on the low-energy side of the former is discussed in terms of an effective mobility edge for exciton relaxation below which excitons cannot relax further within their radiative lifetime