AbstractZnS has been grown on GaAs(100) substrates by atmospheric pressure metal–organic chemical vapour deposition (MOCVD) using dimethylzinc (DMZn) and t‐butyl mercaptan (t‐BuSH). The effects of the reactant gas phase molar ratio and the growth temperature on the characteristics of the material grown have been investigated. The structural quality of the layer is demonstrated by X‐ray rocking curve half‐widths of less than 300 arcsec for the epilayers. There is little significant pre‐reaction and the layers are of excellent surface morphology and layer