Exciton–phonon interaction and energy relaxation in ZnSe-based low-dimensional heterostructures

Abstract

Using a tunable laser excitation we have studied with a high resolution the PL and PLE spectra of localized excitons in ZnCdSe/ZnSe MQWs and ZnSe superlattices (SML) with submonolayer insertions of CdSe. Detailed study of fine structure of PLE spectra and the PL spectra at resonant monochromatic excitation indicates a strong coupling of localized excitons to the phonons all over the Brillouin band, suggesting a tight localization of exciton states. We believe that such a localization is produced by composition fluctuations within QWs or SML, the role of which is strongly enhanced by the low-dimensional character of exciton states.