Thickness dependence of strains in strained-layer superlattices

We present a photoluminescence study of ZnSe-ZnSxSe1−x strained-layer superlattices (SLS’s) grown on 1-μm-thick ZnSe buffer layers using GaAs substrates. The total thickness D of SLS was varied from ∼0.1 to ∼4.6 μm to monitor the behavior of the planar biaxially compressive strains in the ZnSe well layers. We find that SLS’s can exist in a continuous range from a perfectly coherent state to a totally free-standing state as D increases, with these planar strains in the ZnSe layers increasing from almost zero to ∼0.4%. In addition, we also observe clear strain effects produced by the SLS’s on the buffer layers.