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Optical and Electrical Properties of Spin-Coated Co3O4 Thin Films Deposited on Glass Substrate |
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PP: 151-155 |
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doi:10.18576/ijtfst/140211
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Author(s) |
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Farzana Irin,
Md. Ariful Islam Nahid,
Md. Johurul Islam,
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Abstract |
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| Sol-gel vacuum spin coating technique is used to prepare cobalt oxide thin film on glass substrate at a constant speed of 2000 RPM at room temperature. The samples are backed at 50 ̊C for two hours before annealing. The films are annealed at temperatures of 350 ̊C and 650 ̊C to investigate the effect of annealing on structural, morphological, optical and electrical properties. The samples annealed at temperature 650 ̊C show strong XRD diffraction peaks which indicate the spinel cubic structure of Co3O4. SEM study shows that the morphology of the annealed film at 650 ̊C becomes smooth with well oriented grains. The calculated crystallite size from XRD data is about 75 nm. It is also observed from the SEM images that the surface of the films is very rough at low temperature annealing (350 ̊C). The band gap of the film is calculated from optical absorption data. It is seen that the optical band gap varies with film thickness and ranges from 1.9 eV to 2.1 eV. Optical absorption measurement of the annealed film revealed that the nature of the band gap is direct. Electrical properties of the annealed film are measured using four prove technique. It is found that the electrical resistivity of the film at room temperature is 0.018 Ω-cm. The current increases with the increase of measurement temperatures which indicate the semiconducting nature of the film.
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