Improved nonlinear optical absorption mechanism and susceptibility (χ(3)) of CdS nanostructured thin films: Role of zinc doping

Abstract

Thin films of Cd1-xZnxS (CZS) nanostructures were prepared by chemical spray pyrolysis technique with different Zn-doping levels [(Cd1-xZnxS) in ‘x’ ratios of 0.00, 0.01, 0.03, 0.05 and 0.1 for 0%, 1%, 3%, 5% and 10 wt% of Zn respectively] on heated glass substrates at 350 °C. The effect of the Zn dopant on surface morphology and its effect on nonlinear optical (NLO) properties were investigated using atomic force microscopy (AFM) and Z-scan technique by Diode Pumped Solid State (DPSS) continuous-wave laser at 532 nm respectively. The surface roughness was found to be decreased with the increased Zn-doping on CdS. A significant red shift in the band edge and an increase in the transmittance of the films in the visible and NIR regions were also observed. The energy gap (Eg) of the prepared films was estimated and found to be enhanced by 3% i.e. in the range from 2.48 to 2.60 eV. The determined third-order NLO components such as nonlinear absorption coefficient (β), nonlinear refractive index (n2) and the susceptibility χ(3) were found to be in the range from 2.52 × 10−3 to 7.25 × 10−3 (cmW−1), 2.01 × 10−8 to 3.92 × 10−8 (cm2 W−1) and 1.30 × 10−6 to 2.67 × 10−6 (esu) respectively. The results indicate that NLO properties and photoluminescence of the prepared thin films can be tuned with surface morphology. This inspiring NLO results of Cd1-xZnxS thin film is a promising and capable material for optoelectronic device applications.