An analysis of the two‐electron satellites of the dominant donor‐bound exciton line in photoluminescence of ZnSe layers grown on (100)GaAs by molecular‐beam epitaxy indicates that the donor impurity is likely gallium. Strain in the ZnSe epitaxial layers as evidenced by a shift in the positions of the excitonic lines is shown to depend on the growth temperature and is a minimum at about 365 °C. At growth temperatures different from 365 °C theIGa20line is observed shifted by as much as 3 meV. The relatively small shift of ∼0.4 meV in our layers grown at 365 °C may be due to a strain‐relief inelastic process; it is suggested that one possibility might be the formation of a misfit dislocation network at the interface.