Crystal structure and vibrational properties of Cu2ZnSiSe4 quaternary semiconductor

The crystal structure of CuZnSiSe semiconductor, grown by the chemical vapor transport method, was determined by the powder and single-crystal X-ray diffraction and shown to be orthorhombic wurtzstannite (space group P mn2). Lattice dynamics of CuZnSiSe is studied by the low-temperature off-resonant polarized and resonant Raman scattering. Out of the total 45 optical vibrational modes allowed by the symmetry, 37 are observed in the spectra and are assigned to the specific lattice eigenmodes based on their polarization properties and a comparison of frequencies with the results of density functional lattice dynamics calculations. Good agreement between theoretical and experimental mode frequencies is established. The vibrational patterns for the most intense spectral lines in experimental spectra as well as pronounced resonant enhancement of Si-related modes are discussed.