Excitonic Spectrum in CdSe/ZnSe Disordered Superlattices

Abstract

Experimental and theoretical studies of an excitonic spectrum are performed in CdSe/ZnSe submonolayer superlattices. Photoluminescence excitation spectra measured in the structures are compared with simulations carried out within the effective mass approximation, using a model with laterally homogeneous ZnCdSe graded-composition layers. The structure parameters used in the model are obtained from X-ray diffraction studies. The agreement between theory and experiments is satisfactory for superlattices with CdSe layers thinner than 0.5 monolayer. The samples with thicker layers display a red shift 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.