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

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 supe rlattices (SML) with submonolayer insertions of CdSe. Detailed study of fin e structure of PLE spectra and the PL spectra at resonant monochromatic exc itation indicates a strong coupling of localized excitons to the phonons al l over the Brillouin band, suggesting a tight localization of exciton state s. We believe that such a localization is produced by composition fluctuati ons within QWs or SML, the role of which is strongly enhanced by the low-di mensional character of exciton states. (C) 2000 Elsevier Science B.V. All r ights reserved.