Structural, optical and dielectric properties of Zn-doped NiO thin films synthesized via sol-gel route

Abstract

In this study, pure and Zn-doped nickel oxide thin films have been prepared on glass slides using the sol-gel spin coating process. The effects of Zn doping level concentration (0, 1, 3, and 5%) on structural, morphological, optical, and dielectric properties were studied. The X-ray diffraction patterns revealed that all synthesized films are polycrystalline and correspond to the cubic crystal structure with predominant orientation along the (200) plane. Besides, it was found that with the increase of Zn doping concentration, a variation in the values of several structural parameters such as the crystallite size, the lattice constant, and the strain was observed. The surface morphology examined by scanning electron microscope (SEM) reveals that the deposited film becomes dense, smooth, and agglomeration is increased as the Zn doping level increases. FT-IR analyses confirm the existence of Ni-O bonds. From UV-vis measurements, it is found that all samples exhibit highly optical transmission, more than 80% in the visible region, while the optical band gap values vary from 3.76 to 3.93eV as a function of Zn doping content. Further, the refractive index, extinction coefficient, and dielectric constants were also determined.