Structural, Electronic and Optical Characterization of ZnO Thin Film-Seeded Platforms for ZnO Nanostructures: Sol-Gel Method Versus Ab Initio Calculations

Zinc oxide thin films were prepared on glass substrates by sol-gel dip coating technique. ZnO solution was prepared using zinc acetate dihydrate, ethanol and ethanolamine as the starting material, solvent and solution stabilizer, respectively. The samples were annealed at various temperatures for various times to reach the best structure for ZnO. X-ray powder diffraction, scanning electron microscopy and energy dispersive x-ray analysis were used to investigate the structural properties. Upon annealing, we found that the films exhibit a hexagonal structure. Vienna ab initio simulation package based on density functional theory and generalized gradient approximation was used to investigate the structural and electronic properties of wurtzite ZnO structures. The experimental lattice parameters of our samples are found to be in good agreement with ab initio calculated parameters. The ultraviolet-visible spectroscopy (UV-Vis) spectrophotometer measurements were performed to investigate the optical properties of ZnO thin films. We found that the index of refraction of annealed ZnO thin films exhibits values ranging between 1.5 and 2.2. Our structural and optical results indicate that ZnO films could be used as seeded platforms for growing ZnO nanostructures using a simple hydrothermal method.