Growth of Cu2ZnSnS4 crystals by the directional freezing method with an induction heater

Copper zinc tin sulfide (Cu2ZnSnS4: CZTS) crystals were prepared from a Sn solution in a vertical induction furnace by a directional freezing method. The CZTS crystal structure and properties were analyzed by using x-ray diffraction (XRD) and Raman shift measurements. The lattice constants of a- and c-axes calculated from XRD analysis were a = 5426 +/- 0.010 angstrom and c=10.847 +/- 0.021 angstrom. From the Raman scattering spectrum, five CZTS-like-phase peaks at 252 cm(-1)(E), 287 cm(-1) (A), 338 cm(-1) (A), 351 cm(-1) (E), and 368 cm(-1) (B) were observed. Second phase Raman peaks due to Sii Sy corresponding to the Snrich CZTS crystals were also observed, but no other secondary phase Raman peaks were found. Overtone Raman peaks up to the fourth multi-phonon were measured in the first time. Although our grown CZTS crystals included secondary phases of Sn compounds, CZTS crystal quality was remarkable. (C) 2014 Elsevier B.V. All rights reserved.