The use of surfactants to control specific aspects of the vapor-phase epitaxial growth process is beginning to be studied for both the elemental and III/V semiconductors. To date, most reported surfactant effects for semiconductors relate to the morphology of the growing films. However, semiconductor alloys with CuPt ordering exhibit much more dramatic effects. The change in the CuPt order parameter induced by the surfactant translates into a marked change in the band-gap energy. Previous work concentrated on the effects of the donor tellurium. Te is less than ideal as a surfactant, since the change in band-gap energy is coupled to a large change in the conductivity. This letter presents the results of a study of the effects of an isoelectronic surfactant on the ordering process in GaInP. Sb has been found to act as a surfactant during organometallic vapor-phase epitaxial growth. At an estimated Sb concentration in the solid of 1 10 ✁ 4 , order is eliminated, as indicated by the band-gap energy. Surface photoabsorption ✂ SPA✄ data indicate that the effect is due to a change in the surface reconstruction. Adding Sb leads to attenuation of the peak at 400 nm in the SPA spectrum associated with ☎ 1 10✆ P dimers. The addition of Sb during the growth cycle has been used to produce a heterostructure with a 135 meV band-gap difference between two layers with the same solid composition.