Structural characterization of the high-temperature modification of the Cu2ZnGeTe4 quaternary semiconductor compound

A combined study of the X-ray powder diffraction, differential thermal analysis, optical absorption, and Raman spectroscopy of the high-temperature modification of Cu2ZnGeTe4 quaternary semiconductor, obtained by fast quenching from 820 K to ice water temperature, has been done. It has been found that this phase crystallizes in a tetragonal kesterite-type structure. From the analysis of the absorption coefficient spectra, the band gap energy of this material at room temperature has been found to be 1.49 eV. An optical transition from defect acceptor states to the conduction band is also observed below the fundamental absorption edge. Three strongest Raman lines observed at 116, 119, and 139 cm−1 have been assigned to the A-symmetry modes. Also, lines at 81, 89, 97, and 263 cm−1 tentatively ascribed as B or E-symmetry modes have been detected from the spectrum. The presence in this high-temperature modification of ZnTe and Cu2GeTe3 secondary phases has been detected by both XRD and Raman spectroscopy.