Zn1−xCdxSe (x≈0.5), a II–VI wide band gap semiconductor, is grown lattice matched by molecular beam epitaxy on (001) InP substrates. The effect of incorporating an InP buffer layer on structural and optical properties of the ZnCdSe films is studied. Transmission electron microscopy shows that a reduction in the density of stacking faults by two orders of magnitude (from5×109down to5×107/cm2) is realized by use of the buffer layer. Grown-in Shockley-type stacking faults are the only defects observed in the ZnCdSe. The (004) x-ray diffraction rocking curve becomes as narrow as 73 arcsec, and the photoluminescence emission peak becomes narrower and more intense. The lower defect density is attributed to the overall improved InP surface allowing for better two-dimensional nucleation of II–VI growth.©1997 American Institute of Physics.