Optical properties of sprayed CuInS2 thin layers

Thin layers of copper indium disulphide were prepared on Pyrex glass substrate at 320 deg C by the chemical reactive spray process from an aqueous solution containing cuprous and indium chlorides, and thiourea. Films bulk and surface were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) in order to understand the effect of layers microstructure on their optical properties. In the present study, we attempted to interpret the reflectance and transmittance of sprayed CuInS2 films. We showed that the optical spectral profiles of such material are highly related to the optical scattering of light. Indeed, by taking into account the surface roughness and assuming the layer as an effective medium composed of CuInS2 crystallites with gaseous inclusions, we have practically reproduced R(lambda) and T(lambda) spectra.