Opto-dielectric-nonlinear properties of Na–Zn–CdS alloys nanostructure thin films: Role of Zn doping

Abstract Na–Zn–CdS alloys nanostructure films with different doping concentration of Zn (Zn = 1, 2, 3 and 4 wt %) were developed. Structural investigation of films showed that the films have broadened peak at 2θ angle ~26.53°along with cubic zinc blende structure. Grain size of films were found in few nanometer range, which was confirmed from SEM. The vibration spectra of films revealed the characteristics peaks of CdS which are centered at 308-301 cm−1 and first overtone at 604-613 cm−1. The band gap values were obtained in the range of 2.40–2.46 eV. A broadening in optical band gap was observed with increase in Zn concentration. Third-order nonlinear optical susceptibility χ(3) and refractive index n(2) were obtained over the range of 2.92 × 10−13-1.0 × 10−11 esu, and 6.78 × 10−12-7.22 × 10−10 esu, respectively. Photoluminescence spectra of films exhibited the band to band transition with deep level emission (DLE) within the range of 554–568 nm for all films.