Photoluminescence, infrared reflectivity, and Raman spectra of the ordered vacancy compound CuGa3Se5

The photoluminescence (PL), infrared reflectivity (IR), and Raman spectra of the ordered vacancy compound CuGa3Se5 have been studied. Analysis of the data indicates that the main PL emission is due to a donor-acceptor pair recombination. Donor and acceptor levels with activation energy of 15 and 300 meV, respectively, were estimated. The lattice vibrational modes of this compound have also been obtained at 300 K by a combined analysis of IR and Raman spectra. Lines common to both spectra, observed at 48, 64, 105, 142, 187, 200, 218, 250, and 274 cm−1, were identified with E or B2 modes. The most intense peak at 166 cm−1 and those observed at 72 and 90 cm−1, which are only Raman active, are assigned to the A1 and B1 modes, respectively.