Structural, optical and electrical properties of CuInS_2 thin films prepared by chemical spray pyrolysis

摘要

Polycrystalline CuInS_2 thin films were prepared by chemical spray pyrolisis (CSP) on glass sustrate from the ethanol aqueous solution containing CuCl_2, InCl_3 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 CuInS_2 and In_2S_3, the In_2S_3 content in the film decreased with Cu/In ratio. Appearance of Raman peaks at 288 and 298 cm~(-1) indicated that the films contained CuInS_2 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 CuInS_2 bulk crystal. Resisitivity of the Cu-rich films without In_2S_3 secondary phase was 0.2-5 Ωcm.