Effect of the thickness on the optical properties of nanostructure CuS thin films

Abstract

At this work, nanostructure copper sulfide (CuS) thin films at different temperature of substrate and thickness (120,200,750) nm have been acquired by chemical spray pyrolysis method. The X-Ray Diffraction (XRD) measurements of all films appeared polycrystalline structure and possessed a hexagonal phase with strong crystalline orientation (103) with crystal size equals approximately 80 nm by using atomic force microscopy (AFM). The linear optical measurements showed that nanostructure CuS thin films have direct energy gap. The energy gap was decreased with increasing thin films thickness. Nonlinear optical properties experiments were performed using Q-switched 1064 nm Nd:YAG laser Z-scan system. The nonlinear refractive index (n₂) and nonlinear absorption coefficient (?) were estimated at different thicknesses of nanostructure CuS thin films for different intensities of laser. n₂ and ? were decreased with increasing intensity of incident laser beam . Also they were reduced with increasing the nanostructure CuS thin films thicknesses. Also the type of ? were two and three photon absorption , type of n₂ were positive nonlinear reflective index and n₂ were self-focusing nonlinear refractive index  for all samples .