Emission and opto-dielectric nonlinearity in 2D Cd-ZnO-Na nanostructures: an effect of Na doping

Cd-ZnO-Na alloy nanostructured thin films were synthesized via sol-gel spin coating method on glass substrates and the effect of Na (1, 2 and 3 wt%) doping variation on linear, nonlinear optical, opto-dielectric, and emission properties of the films was investigated. The variations in physical properties with different Na doping concentrations were analyzed using X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), FT-Raman, UV-Vis, and photoluminescence spectroscopy. From XRD patterns, it was observed that the growth of the films occurs along (002) plane with hexagonal wurtzite structure. High percentage of transmittance (viz. 85 to 90%) was recorded for all as grown films. However, the estimated bandgap energy of the films was found to decrease from 3.37 to 3.30 eV with increasing Na doping concentration from 1 to 3 wt%. Emission spectra of the films show an intense and sharp peak near band emission (NBE) at 389 nm whereas a low intense peak was observed at 475 nm. The intensity of NBE peak specifies the significant enhancement in photoluminescence properties of the grown films with increasing Na doping concentrations. Nonlinear optical parameters of the Cd-ZnO-Na films such as chi(3)andn(2)showed substantial improvements, which were deduced and obtained in the range 1.11 x 10(-14)-1.91 x 10(-12)esu and 5.20 x 10(-13)-3.19 x 10(-11)esu, respectively. The achieved improvement in the grown ZnO films via co-doping with Cd and Na makes them highly suitable candidates for optoelectronics devices applications.