A systematic dependence of the density and type of stacking fault defects with substrate surface chemistry and film growth mode was observed in ZnSe‐based films grown on GaAs substrates. Namely, the density of Frank‐type stacking faults is very large for films grown on Ga‐rich surfaces, but is very low for films grown on As‐stabilized surfaces exposed to Zn prior to the growth of the film. In contrast, the density of Shockley‐type stacking faults increases for films grown by 3D growth mode at the initial stages of growth, but decreases greatly if the films are grown by the layer‐by‐layer growth mode. Films with stacking fault densities as low as 104/cm2were obtained by growing the films by the layer‐by‐layer growth on GaAs epilayers with As‐stabilized surfaces that were exposed to Zn for 1–2 min prior to the growth of the films. ©1995 American Institute of Physics.[S0003‐6951(95)00548‐6]