We investigated the influence of the temperature of the ZnSe cap layer growth on the Cd distribution in CdSe/ZnSe heterostructures by transmission electron microscopy, high-resolution X-ray diffraction and photoluminescence spectroscopy. ZnSe buffer layers were grown by molecular-beam epitaxy on GaAs (0 0 1). For the CdSe layers and ZnSe cap layers, migration-enhanced epitaxy was used. Increasing the temperature for the cap layer growth reduces the Cd concentration and the total CdSe amount in the (Cd,Zn)Se layers leading to a blue shift of the photoluminescence spectra. This is owing to a stronger Cd desorption during the cap layer growth for a higher substrate temperature. (C) 2003 Elsevier B.V. All rights reserved.