Effect of Cu and In content in precursor solution on the structural and optical properties of CuInS2 in CH ordered nanostructured films

Abstract

CuInS2 nanostructured films were prepared by Ultrasonic spray pyrolysis (USP) method. Variation of structural and optical properties of the CuInS2 films including Cu and In in the precursor solution were investigated. The films were found to be p-type by using hot probe method. Raman Spectroscopy and X-ray diffraction (XRD) methods have been chosen to study the structural properties of the films as Raman spectroscopy allows the investigation of the near surface region, while XRD is a bulk-sensitive method. Optical properties were obtained from UV–vis absorption, transmittance and reflectance spectra of the nanostructured CuInS2 films. The films have polycrystalline structure with a preferential growth along the (112) plane. The grain size of all the films was found to be lower than 15nm. The Raman peak at 296cm−1 has been assigned to the A1 mode of the CuInS2 in CH-ordered. Absorption coefficient of the films have increased by increasing photon energy and decreasing wavelength. The optical constants of the films such as refractive index, extinction coefficient as well as the real and imaginary parts of dielectric constant have changed by increasing the In content of the precursor solution.