Exciton–phonon luminescence and Raman scattering in CuGaS2 crystals

Photoluminescence and resonance Raman scattering spectra of CuGaS2 crystals are investigated at low temperature (10 K) under the excitation with the radiation from a spectral interval obtained by passing the radiation of an incandescent or xenon lamp through a monochromator. The thermalized luminescence of the Γ4 and Γ5 excitons was revealed under the excitation by an interval of photon energies higher than the energy of the ground state of long-wavelength Γ4 excitons (ωТ(Γ4) + 1ELO1). The energy conversion between the polariton modes in luminescence and resonance Raman scattering spectra is considered.