Photoreflectance (PR) spectroscopy has been developed as a powerful technique for the characterization of the heteroepitaxial layer of the Cu–III–VI2semiconductors having the chalcopyrite structure. PR measurements have been carried out in the energy region near the fundamental absorption edge at 77 K for the heteroepitaxial layers of CuAlSe2, CuGaSe2, CuGaS2, and CuAlS2grown on GaAs and GaP substrates by means of the low‐pressure metalorganic chemical vapor deposition. Crystal quality, stress, and the crystallographic orientation have been well characterized, based on the analysis of the PR spectra in terms of transition energy, intensity, and broadening parameter. ©1996 American Institute of Physics.