Vibrational properties of CdGa2S4

Abstract

Polarization-dependent infrared reflectivity spectra of CdGa2S4 are measured at 300 K in the wavenumber range from 180 to 500 cm−1. The analysis of the spectra yields three E and four B modes in this frequency range. The results are compared with previously published data and a final identification of the infrared active modes in CdGa2S4 is proposed. It is shown that the two-phonon absorption spectra of CdGa2S4 can be interpreted in terms of zone-centre two-phonon combination modes. The relation between the lattice vibrational properties of chalcopyrite and defect-chalcopyrite compounds is discussed.