Synthesis of CuInS2 by chemical route:: optical characterization

CulnS(2) powder was prepared by wet chemical route. The chalcopyrite structure of the powder was revealed by XRD studies. Raman measurements of the powder sample indicated four prominent peaks at 292, 305, 340 and 472 cm(-1). The possible origin of the 305 cm(-1) peak was investigated and was found to be some local vibration in the structure. The peaks at 292 and 340 cm(-1) were ascribed to A(1) and B-2 modes, respectively. The peak at 472 cm(-1) which was due to the formation of SO4-2 ion at lower pH value of the precursor solution could be eliminated by using pH > 11.0. Photoluminescence (PL) studies of the CuInS2 powder indicated two distinct peaks at 1.49 and 1.42eV. Post deposition annealing treatment in H-2 atmosphere revealed the formation of excess sulphur vacancy leading to the peak at 1.42 eV in the PL spectra while 0, annealing of the powder created a deep defect level at 1.10 eV. Thick CuInS2 films were prepared by Doctor's blade technique. Optical transmittance studies of these films indicated direct allowed transition at similar to 1.5 eV. (C) 2003 Elsevier B.V. All rights reserved.