Linear, third order nonlinear optical and photoluminescence properties of Cd0.99Zn0.09S/ZnO nanocomposite thin films for optoelectronics applications

Abstract

Cd0.99Zn0.01S/ZnO nanostructured films were developed by solution processing method on ITO/glass substrates with different ZnO thicknesses. Structural, linear, nonlinear optical and photoluminescence properties of the as grown films were analyzed. In x-ray diffraction patterns, Cd0.99Zn0.01S and ZnO peaks were observed clearly. The grain size of the films was estimated to be in the range of 23-25 nm. 2D atomic force microscopy images of the films confirmed the growth of nano size grains. Tauc's plot of the films reveals that the band gap energies are in the range of 2.49 -2.54 eV. Photoluminescence spectra of films showed interesting reduction in the visible emission along with an enhancement in the UV emission with increasing ZnO thickness. The nanocomposite Cd1-xZnxS/ZnO thin film with 20 nm thickness shows high transmittance of about 70 %. Nonlinear optical parameters such as third order nonlinear optical susceptibility, χ(3) and nonlinear refractive index n2 were also roughly estimated. The values of χ(3) and n2 parameters were found to be in the range of 1.73 × 10−13-1.09 × 10−11 esu and 2.6 × 10−12-1.78 × 10−10 esu, respectively.