PHOTOLUMINESCENCE OF WIDE BANDGAP II-VI SUPERLATTICES

Photoluminescence (PL) and PL decay measurements are used to characterize typical samples of wide gap II-VI strained layer superlattices (SLSs). The results show that good quality material is obtained for SLSs of ZnSe/ZnS, CdSe/CdS (hex), ZnSe/CdSe and ZnS/CdS using atmospheric pressure MOCVD. Quantum confinement in SLSs is confirmed by the peak shift, temperature dependence and decay characteristics of the exciton luminescence. The PL intensity at low temperatures ( <20 K) shows a weak bistable dependence at low excitation power density in several samples. Transition from excitonic to free-particle behaviour is clear at elevated temperatures. The decay curves are non-exponential, indicating the influence of inhomogeneities and/or impurities. However, lifetimes are uniformly longer than in comparable epilayers. In principle, our results allow us to construct a general band offset diagram for the Zn(Cd)S(Se) family of superlattices. © 1989.