Excitonic spectrum in CdSe/ZnSe disordered superlattices

Experimental and theoretical studies of an excitonic spectrum are performed in CdSe/ZnSe submonolayer superlattices. Photoluminescence excitation spec tra measured in the structures are compared with simulations carried out wi thin the effective mass approximation, using a model with laterally homogen eous ZnCdSe graded-composition layers. The structure parameters used in the model are obtained from X-ray diffraction studies. The agreement between t heory and experiments is satisfactory for superlattices with CdSe layers th inner than 0.5 monolayer. The samples with thicker layers display a red shi ft of the experimental lowest-energy exciton and quenching of its intensity as compared to the simulations. The observed disagreement is discussed in terms of lateral inhomogeneity of the CdSe-based layers.