High reflectivity ZnS/ZnSe distributed Bragg reflectors (DBR) have been grown on GaAs(100) substrates using metallorganic chemical vapour deposition technique. It was found that the surface roughness, which limits the ZnS/ZnSe DBR mirror reflectivity, may be reduced using the interruption of chalcogen-contained flow before each successive layer growth. The DBR mirrors have been obtained with reflectivity as high as 99% and 94% at the wavelengths of 478 nm and 520 nm, respectively. The ZnCdSe/ZnSe QW structure grown on the ZnS/ZnSe DBR mirror manifests cathodoluminescence at room temperature whose intensity is an order of magnitude less than that of the similar structure grown on ZnSe buffer. Large lattice mismatch between ZnS and ZnSe layers results in high density of defects in ZnCdSe/ZnSe QW structures grown on. the DBR
