Photoreflectance of CuInS2 single crystal prepared by traveling heater method Original Research Article

Temperature dependence of photoreflectance (PR) measurements has been carried out on the high-quality CuInS2 single crystals grown by traveling heater method. Energies and broadening parameters of the A and BC excitons associated with the valence to conduction band transition have been obtained. PR spectra were fitted to the first derivative of Lorentzian. This result is in good agreement with the fact that the transitions are excitonic. At low temperature (8–80 K), PR peaks are very sharp with a small broadening parameter (ΓA=1.6 meV). As temperature is increased in excess of 100 K, PR spectra become broad gradually and A and BC transitions cannot be clearly resolved (150–300 K). PR spectra are discussed with relation to the photoluminescence spectra.