Selectively grown ZnS-based II-VI semiconductor photonic dot structures, which have ZnSe active layers inside, were studied. The luminescence from the photonic dot structures showed modulation of the spontaneous emission at the optical resonance wavelengths, which was observed by the mu-photoluminescence measurements. However, the modulation of the spontaneous emission was weak. This was caused by the geometry of the ZnSe layers. The ZnSe layers were grown isotropically on (0 0 1) and {0 3 4} ZnS planes. The luminescence from the ZnSe/ZnS photonic dots, being superimposed more with the one from the layers grown on the {0 3 4} ZnS side facets, was not coupled efficiently with the cavity modes. The modulation effects were much improved by etching the pyramids to avoid the luminescence from the side ZnSe layers on the {0 3 4) facets.