We report here a study of the Raman spectra of ternary Cu–In–S and Cu–In–Se polycrystalline film compounds as a function of thex=[In]/{Cu]+[In]} ratio. Using these spectra we were able to identify, with high resolution inx, the phases present in the films. We found that the single phase of chalcopyrite CnInSe2exists over the fairly wide composition range of 0.48⩽x⩽0.55, and that the lattice disorder increases with the increase of In content. No such single phase range was found for the Cu–In–S films. Considering the electrical properties of these materials aroundx=0.5, it is concluded that the native defect model accounts for the electrical properties of the Cu–In–Se films but does not account simply for the electrical properties of the Cu–In–S films. ©1996 American Institute of Physics.