CdSe epilayers were grown on GaAs(0 0 1) substrates by molecular beam epitaxy (MBE) in a wide range of VI/II beam-equivalent-pressure (BEP) ratio from 1.1 to 8.5. X-ray diffraction (XRD) theta-2 theta scan reveals all the CdSe samples possess cubic zinc blende structure with (0 0 1) orientation. The film grown at a low VI/II ratio of 1.1 has rough surface with a three-dimensional (3D) growth mode, while two-dimensional (2D) growth can be established under Se-rich conditions at higher Se/Cd BEP ratios over 4.4. The growth rate increases monotonically with the VI/II ratio and becomes saturated when the ratio is raised to 8.5. The sample grown at a VI/II ratio of 8.5 shows the narrowest full-width at half-maximum (FWHM) of X-ray rocking curve (XRC) for (0 0 4) reflection. No near-band-edge (NBE) emission of CdSe is observed for the sample prepared at a low ratio of 1.1. The NBE emission from cubic CdSe at around 1.67 eV appears and its intensity is markedly enhanced by elevating the VI/II ratio. It is suggested that CdSe epilayer with good structural and optical properties can be prepared under a large VI/II BEP ratio. (C) 2011 Elsevier B.V. All rights reserved.