Investigation on the effect of annealing period on the structural and optical properties of ZnO thin films prepared using a polymer precursor

Abstract

Numerous synthesis strategies including sputtering,molecular beam epitaxy,chemical vapour deposition, pulsed laser deposition etc., have been reported to grow high quality ZnO thin films[1]. However among these mounted synthesis strategies, simple and price powerful path to develop ZnO thin films by way of usage of cheaper, non poisonous and environmentally benign precursors are nevertheless the important issues. This work advise a simple and novel technique to the fabrication of ZnO thin films with the aid of poly vinyl alcohol (PVA) as precursor. This article also investigate the impact of annealing period on the structural and optical properties of grown films by analyzing XRD, UV absorption and photo luminescence spectra. The XRD pattern reveals poly crystalline hexagonal wurtzite structure. The particle size and stress values varies with changes in annealing period. The values of UV absorption spectra are utilized to plot Tauc plot to get the band gap of the films. The band gap shows significant decrease from 3.35ev to 3.10ev with increase in annealing period. The films shows good transmittance >75% and transmittance increase as the annealing parameter increases. The PL spectra have peaks in UV and visible regions,. the mechanism behind these emission peaks are also discussed.