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Nanocrystalline ZnO Thin Film Synthesis Using Glycerol in Aqueous Polymeric Precursor Processing
Author(s) -
Choppali Uma,
Gorman Brian P.
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02523.x
Subject(s) - materials science , thin film , nanocrystalline material , crystallite , wurtzite crystal structure , crystallinity , chemical engineering , fourier transform infrared spectroscopy , annealing (glass) , crystallization , photoluminescence , aqueous solution , microstructure , thermogravimetric analysis , spin coating , analytical chemistry (journal) , nanotechnology , composite material , zinc , organic chemistry , metallurgy , optoelectronics , chemistry , engineering
Synthesis of high‐quality ZnO thin films via simple and cost effective processing technique is a major challenge. In this work, the preparation of nanocrystalline ZnO thin films by a novel polymeric precursor processing using glycerol as chelating agent is presented. The process has advantages of being cost‐effective and environment friendly. ZnO thin films were prepared by a single spin‐coating deposition of aqueous polymeric precursor prepared with zinc nitrate [Zn(NO 3 ) 2 ] and glycerol as chelating agent. The thermal decomposition of polymeric precursors was studied by thermogravimetric analysis and Fourier transform infrared (FTIR) spectroscopy. Annealing of these films were performed over the range of 300°–600°C, and the effect of annealing on the degree of crystallization, surface morphology, crystallite size, and optical properties was investigated. X‐ray diffraction analysis shows that the thin films are polycrystalline with wurtzite structure. The thin films are 80% dense, have crack free microstructure, and transparency of >85% in the visible region. These films exhibit absorption edge at 375 nm. On measuring at room temperature, the optical band gap energy of ZnO thin films, annealed at 450° and 600°C, was determined to be 3.295 and 3.267 eV. Room temperature photoluminescence spectra of these films show strong UV emission and a broad yellow‐green emission in the range 525–600 nm. The intensity of UV emission peak increases with increase in annealing temperature that is attributed to an improvement in crystallinity.