Mirror-like hexagonal CdS. ZnCdS layers and CdS/ZnCdS quantum well (QW) structures have been grown on CdS(0 0 0 1) and ZnCdS(0 0 0 1) substrates by metalorganic vapour-phase epitaxy. CdS and ZnCdS epilayers with high cathodoluminescence (CL) intensity at room temperature have been obtained by optimization of growth conditions. Two additional emission lines. not observed in US bulk crystals. appear in low temperature CL spectra. These lines can be ascribed to thin cubic layers due to stacking faults at growth of the hexagonal US epilayer. CL spectra of CdS/ ZnCdS QW structures contain intense US QWs emission lines. With increasing excitation intensity the short-wavelength shift of the QW emission line is a manifestation of internal piezoelectric effect. (C) 2002 Elsevier Science B.V. All rights reserved.