Characterization of CuInS2 thin films prepared by ion layer gas reaction method

Ion layer gas reaction (ILGAR) method for CuInS2 films was developed by using ethanol as solvent. The influences of [Cu] / [In] ratio in ethanol solution on structural, chemical, topographical, optical and electrical properties of CuInS2 thin films were investigated. X-ray diffraction and X-ray photoelectron spectroscopy results showed that all CuInS2 thin films derived from different [Cu] / [In] ratios were sphalerite with preferred orientation (112). Scanning electron microscopy revealed that the microstructure and the growth rate of the films depended on the relative amounts of copper in the solution. When [Cu] / [In] ratio was 1.50 growth rate of the film was about 30 nm/cycle and the film was uniform, compact and good in adhesion to the substrates. The absorption coefficients of CuInS2 films estimated from transmittance spectra were more than 104 cm− 1, and the films behaved with p-type conductivity. The band gap Eg changed from 1.30 to 1.40 eV and the dark resistivity decreased from 3.1 to 0.04 Ω cm with increase of [Cu] / [In] ratio.