Growth Of ZnO Nanostructured Thin Films By Non Conventional Sol-Gel Method And The Effect Of Annealing Temperature On Its Properties

Abstract

Abstract The present work demonstrates the growth of Zinc oxide (ZnO) thin films from its powder precursor by using non-conventional sol-gel technique. The structural, morphological and optical properties of obtained thin films were studied under different annealing temperatures. X-ray diffraction (XRD) analysis confirmed hexagonal wurtzite structures for both annealed and pristine thin films. The crystallite size was found between 14 and 16 nm. Field Emission Scanning Electron Microscope (FESEM) images showed that the films have approximately uniform morphologies, consisting in several flower-like aggregates with nanosized multi petals. From the optical properties it was found that with the increase in the annealing temperature there is an increase in the absorption coefficient in the visible wavelength range. It was also noticed that the increase in annealing temperature caused a decrease in bandgap (Eg) and increase in Extinction coefficient. Urbach energy decreased with the increase annealing temperature up to 250°C, afterwards the Urbach energy increased with the increase in the annealing temperature. The causes for these observations are discussed.