Micro-photoluminescence excitation spectroscopy on asymmetric absorption line shapes of weakly localized excitons in a quantum well

Micro-photoluminescence (PL) and micro-PL excitation (PLE) spectra were measured systematically in a 5 nm GaAs/AlAs single quantum well (QW) to investigate the predicted effect of asymmetric exciton absorption line shapes having high-energy tails due to weak localization of exciton center-of-mass motion by interface roughness. We found a characteristic change in the asymmetric shapes as the QW-interface coverage by monolayer terraces varied. Via spectral fitting using a reported model, we quantitatively obtained a localization length varying between 4-15 nm, and verified the validity as well as limitation of this model.