Resonant Raman study of low-temperature exciton localization in GaAs quantum wells

We have observed an unexpected temperature dependence in the intensity of Raman scattering resonant with the ground-state exciton in GaAs-${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As quantum-well heterostructures. We show that the temperature dependence is related to the homogeneous linewidth for quantum-well excitons and yields new insight into low-temperature exciton localization.