Photoluminescence, FTIR and X-ray diffraction studies on undoped and Al-doped ZnO thin films grown on polycrystalline a-alumina substrates by ultrasonic spray pyrolysis
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Date
2010-06-17
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Abstract
Undoped and aluminum-doped zinc oxide (ZnO) thin films have been grown on polycrystalline
a-alumina substrates by ultrasonic spray pyrolysis (USP) technique using zinc acetate dihydrate and
aluminum chloride hexahydrate (Al source) dissolved in methanol, ethanol and deionized water. A
number of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier
transform infrared (FTIR) spectroscopy, and photoluminescence (PL) were used to characterize the
obtained ZnO thin films. It was seen that the orientation changed with increase in substrate
temperature. During the ZnO deposition Zn source reacted with polycrystalline a-Al2O3 substrate to
form an intermediate ZnAl2O4 spinel layer. It has been interestingly found that the intensity of green
emission at 2.48 eV remarkably increased when the obtained ZnO:Al films were deposited at 380 1C.
The FTIR absorbance intensity of spectroscopic band at 44776 cmÿ1 is very sensitive to oxygen
sublattice disorder resulting from non-stoichiometry, which is consistent with the result of PL
characterization