Influence of calcination ambient and film thickness on the optical and structural properties of sol-gel TiO{sub 2} thin films

Influence of both calcination ambient and film thickness on the optical and structural properties of sol-gel derived TiO{sub 2} thin films have been studied. X-ray diffraction results show that prepared films are in an anatase form of TiO{sub 2}. Films calcined in argon or in low vacuum ({approx}2 x...

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Bibliographic Details
Published in:Materials research bulletin 2007-01, Vol.42 (1)
Main Authors: Sreemany, Monjoy, Sen, Suchitra
Format: Article
Language:English
Subjects:
AGGLOMERATION
ARGON
CALCINATION
MATERIALS SCIENCE
MICROSTRUCTURE
NANOSTRUCTURES
PARTIAL PRESSURE
PARTICULATES
REFRACTIVE INDEX
SCANNING ELECTRON MICROSCOPY
SOL-GEL PROCESS
THICKNESS
THIN FILMS
TITANIUM OXIDES
VOIDS
X-RAY DIFFRACTION
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Summary:Influence of both calcination ambient and film thickness on the optical and structural properties of sol-gel derived TiO{sub 2} thin films have been studied. X-ray diffraction results show that prepared films are in an anatase form of TiO{sub 2}. Films calcined in argon or in low vacuum ({approx}2 x 10{sup -1} mbar) are found to be smaller in crystallite size, more transparent at low wavelength region of {approx}300-450 nm, denser, have higher refractive index and band gap energy compared to air-calcined films. Scanning electron microscopic study reveals that surfaces of TiO{sub 2} films calcined in argon or in low vacuum are formed by densely packed nano-sized particulates. Presence of voids and signs of agglomeration can be seen clearly in the surface microstructure of air-calcined films. In the thickness range {approx}200-300 nm, band gap energy and crystallite size of TiO{sub 2} films remain practically unaffected with film thickness but refractive index of thinner film is found to be marginally higher than that of thicker film. In this work, it has been shown that apart from temperature and soaking time, partial pressure of oxygen of the ambient is also an important parameter by which crystallite size, microstructure and optical properties of the TiO{sub 2} films may be tailored during calcination period.
ISSN:0025-5408
1873-4227
DOI:10.1016/j.materresbull.2006.04.033