Influence of annealing process on structural, optical and electronic properties of nano-structured ZnO films synthesized by hydrothermal technique: Supported by DFT study

Abstract

The annealing temperature effect on the physical properties of zinc oxide (ZnO) nanorods is experimentally and theoretically investigated. Different diagnostics techniques such as XRD, UV–Vis, SEM, and Hall effect measurements were employed to analyze the influence of annealing temperature on the structural, optical, and electrical properties of ZnO nanorods films. Additionally, Density Functional Theory (DFT) was also applied to calculate ZnO’s lattice parameters, energy gap, and optical properties depending on annealing temperature.Experimental results show that the variation of the optical band gap of the fabricated samples has the same behavior within the theoretical calculation. X-ray diffraction (XRD) results reveal that the pure film is crystallized in the hexagonal phase of ZnO with the miller plane (002).The crystallite size is affected by annealing temperature.The field emission scanning electron microscopy (FESEM) shows nanorods formation on the surface of the films. The transmittance properties of the studied films are dependent on the annealing temperature in the ZnO films from UV–Vis data, confirming the band gap’s widening effect with annealing. Overall, the experimental and theoretical findings support each other.