Structural, optical and electrical properties of CuInS2 thin films prepared by chemical spray pyrolysis

Polycrystalline CuInS2 thin films were prepared by chemical spray pyrolisis (CSP) on glass sustrate from the ethanol aqueous solution containing CuCl2, InCl3 and thiourea. Structual, electrical and optical properties were systematically studied in terms of substrate temperature, pH and the ion ratio (Cu/In) of the spray solution. Although the In‐rich films were composed of CuInS2 and In2S3, the In2S3 content in the film decreased with Cu/In ratio. Appearance of Raman peaks at 288 and 298 cm‐1 indicated that the films contained CuInS2 with chalcopyrite and CuAu phases. Typical grain size in the Cu‐rich films was 200 nm. Optical gap energies were approximately 0.1‐0.2eV smaller than the bandgap energy of the CuInS2 bulk crystal. Resisitivity of the Cu‐rich films without In2S3 secondary phase was 0.2–5 Ωcm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)