Crystallographic and optical properties of CuInS 2 ‐Cu 2 ZnSnS 4 crystals

CuInS 2 ‐Cu 2 ZnSnS 4 crystals were synthesized by the pressure‐less sintering method using CuInS 2 and Cu 2 ZnSnS 4 powders grown from each melt. The x values in Cu 2 (2In) x (ZnSn) (1.00− x ) S 4 were evaluated by energy dispersive spectroscopy. Lattice constants were derived from powder X‐ray diffraction analysis by Rietveld method. Lattice constants of CuInS 2 phase changed linearly at x  ≥ 0.49. On the other hand, lattice constants of Cu 2 ZnSnS 4 phase changed almost linearly at x  ≤ 0.37. In Raman spectra, peak positions of A ( I 4 ¯) or A 1 ( I 4 ¯ 2 m ) mode of Cu 2 ZnSnS 4 phase changed toward the lower wavenumber side linearly with increasing x . A 1 mode of CuInS 2 phase became weaker with decreasing x , and disappeared below x  = 0.49. In PL spectra measured at 15 K, broad peaks at about 1.26 eV were observed at 0.00 ≤  x  ≤ 0.85.