Structural, linear and nonlinear optical properties of Zn@CdO nanostructured thin films: a quantitative comparison with DFT

This paper presents experimental and density functional theory (DFT) investigations of Zn doping role in the Zn@CdO ternary system. Zn doped CdO nanostructures thin films with different Zn concentrations were successfully casted on glass substrates by sol–gel spin coating method. Cubic Zn@CdO structured ternary alloyed nanostructures thin films with 0.0, 1.0, 2.0 and 3.0 wt.% Zn concentrations were obtained. An enhancement in the lateral growth of CdO cauliflower-like nanostructures was observed after Zn addition which leads to a growth of nanostructured films with improved continuity. The effect of Zn doping on the linear optical parameters such as the optical band gap, the absorption index and the refractive index were also investigated. A remarkable blue shift in the band edge was observed as Zn is incorporated into the CdO matrix. In addition, the third order nonlinear optical parameters χ⁽³⁾ and n₂ were calculated and found to be about 2.89 × 10^–12–4.33 × 10^–14 esu and 2.89 × 10^–12–4.33 × 10^–14 esu; respectively. A DFT based Wien2k package was utilized to theoretically investigate the lattice parameters, the electronic structure, the absorption index and the refractive index of the Zn@CdO ternary nanoalloys. The role of Zn doping on the aforesaid properties was theoretically investigated for 3.125%, 6.25%, 12.5% and 25% Zn doping concentrations and was compared with the experimentally determined parameters. The combined theoretical and experimental investigations presented herein along with the detailed discussion of the obtained findings would provide a deep understanding of the opto-electronic behavior of the Zn doped CdO nanostructured films as well as their suitability for devices applications.