Effect of annealing temperature on optimizing the structural, linear–nonlinear optical properties of Cd1-xZnxS nanocrystalline thin films

The present work reports the study on effect of annealing at different temperature and dissimilar Cd/Zn ratios on optical linear and nonlinear properties of Cd1-xZnxS (in x ratios of = 0.00, 0.01, 0.03, 0.05 and 0.1 wt. % of Zn) thin films deposited by spray pyrolysis (SP) technique. All the fabricated films are polycrystalline in nature and having a hexagonal crystal structure with the single phase of CdS was confirmed by Powder X-ray diffraction studies (P-XRD). The Scherer rule was used to assess the size of the crystallite and was found to be increasing with increasing annealing temperature. FESEM images display uniform grains and decrease marginally with an increase in doping content and annealing. The optical energy band gap (Eg) of the prepared films ranged from 2.40 eV to 2.64 eV. The laser-induced damage threshold (LDT) value of the annealed Cd1-xZnxS thin film is 0.1520 KW/cm2. The NLO parameters of the prepared samples were calculated at 532 nm from the Z-scan data under solid state continuous wave laser irradiation and the 3rd-order NLO components such as β, $$n_{2}$$ and χ(3) were found to be enhanced with the annealing temperature i.e. from 1.58 × 10−5 to 4.85 × 10−3 (cmW−1), 1.08 × 10−8 to 4.38 × 10−8 (cm2W−1) and 7.22 × 10−7 to 5.94 × 10−6 (esu) respectively. These favourable results of NLO parameters suggests, the current fabricated nanstructured films are capable material for photonic device applications.