Composition of CuInS2 thin films prepared by spray pyrolysis

CuInS2 films were prepared by spray pyrolysis technique using CuCl2, InCl3 and SC(NH2)2 as initial chemicals. The content of Cl, O, C and N impurities in sprayed CuInS2 films were measured by EDS, WDS, RBS and organic elemental analysis. The growth temperatures of 260–280°C result in Cl, C, N content of 8 mass% and the impurity phases contain SCN, CN, NH, SO4 groups as identified by FTIR. The increase in the growth temperature up to 380°C decreases the concentration of Cl, C, N to 1–2 mass%, concurrently leading to oxidation of inorganic and organic phases resulting in O content of 16.7 at.%. The content of impurities originated from precursors is mainly controlled by the growth temperature and in less extent by the Cu/In ratio in spray solution as Cu-rich solutions result in the films with reduced content of organic residues. Thermal treatments in reducing atmospheres at 450°C improves the crystallinity of the films while annealing in flowing H2 effectively reduces the content of Cl and O impurities.