Effect of the growth temperature on chemical composition of spray-deposited CuInS2 thin films

CuInS2 films were deposited by spray pyrolysis method at 250 °C and 350 °C using aqueous solutions of CuCl2, InCl3 and SC(NH2)2 at molar ratio of precursors Cu:In:S=1:1:3 in spray solution. Films were characterized by X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) techniques. According to XPS, the films grown at 350 °C have Cu2+ containing pieces on the surface, the film composition in bulk region is not homogeneous and contains metal bonded oxygen in amount of 5-8 at.%. Deposition at 250 °C reduces the content of oxygen down to ∼ 1 at. %, the films are low-crystalline with uniform distribution of the elements throughout the film and contain some excess of sulfur compared to stoichiometric CuInS2.