The flux parameters employed during molecular beam epitaxy of ZnSe on GaAs control both the heterojunction band alignment and the optical quality of the II–VI wide‐gap layer. Independent optimization of the band discontinuities and ZnSe optical properties was achieved by fabricating a 2‐nm‐thick interface layer in nonstoichiometric conditions to control the band alignment, followed by the optically active layer in near‐stoichiometric conditions. ©1995 American Institute of Physics.