Photoluminescence, infrared reflectivity, and Raman spectra of the orderedvacancy compound CuGa3Se5

The photoluminescence (PL), infrared reflectivity (IR), and Raman spectra o f 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 re combination. Donor and acceptor levels with activation energy of 15 and 300 meV, respectively, were estimated. The lattice vibrational modes of this c ompound have also been obtained at 300 K by a combined analysis of IR and R aman spectra. Lines common to both spectra, observed at 48, 64, 105, 142, 1 87, 200, 218, 250, and 274 cm(-1), were identified with E or B-2 modes. The most intense peak at 166 cm(-1) and those observed at 72 and 90 cm(-1), wh ich are only Raman active, are assigned to the A(1) and B-1 modes, respecti vely. (C) 2000 American Institute of Physics. [S0021-8979(00)05803-5].