This article demonstrates the effect of the thin low-temperature-grown ZnSe buffer layer (LT-ZnSe) in improving crystallinity of ZnSe-based films grown on GaAs substrate. Especially, the density of stacking fault defects, which is normally observed in ZnSe-based films grown on GaAs substrate, can be well reduced by inserting a thin ZnSe buffer layer grown at sufficiently low temperature between ZnSe/GaAs heterostructure. A ZnSe film with stacking fault densities as low as similar to2 x 10(6)/cm(2) was obtained by growing on the LT-ZnSe/GaAs buffer layers, in contrast, similar to8 x 10(8)/cm(2) was obtained by directly growing on GaAs substrate. The Frank-type stacking faults was dominant for films grown with LT-ZnSe, meanwhile, Shockley-type stacking faults was dominant for films grown without LT-ZnSe buffer. At the initial stages of ZnSe growth, three-dimensional growth mode is considerably suppressed with LT-ZnSe buffer. The improvement of crystallinity in the ZnSe film with LT-ZnSe and GaAs buffer is also evidenced by low-temperature photoluminescence spectroscopy and high-resolution X-ray diffraction, which show very large intensity ratio of near-and-edge emission to deep level emission and narrow X-ray diffraction peak width of (004) rocking curve with 92 arcsec, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.