JAST
2012 March;3(1):85-94.
Published online 2012 January 27.
doi:http://dx.doi.org/10.5355/JAST.2012.85
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| Copyright ⓒ 2010 Journal of Analytical Science & Technology |
| Sn-doped Zinc Oxide thin films for LPG sensors |
| R. K. Nath1,*, S. S. Nath2, Kumar Sunar1 |
1Department of Physics, Guru Charan College, Silchar-788004, Assam, India
2Department of Physics, Assam University, Silchar, Silchar-788018, Assam India |
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Corresponding Author:
R. K. Nath ,Email: nathraj2002@gmail.com |
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ABSTRACT |
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| Sn doped zinc oxide (ZnO:Sn) thin films have been prepared by chemical spray pyrolysis technique using Zn(CH3COO)2 as a precursor solution and SnCl4 as a doping solution respectively. The dopant concentration (Sn/Zn at%) is varied from 0 to 1.5 at%. The structural, morphological, optical and electrical properties of the films are explored and then tested for LPG sensing. The resistivity of the Sn-doped films decreases with the Sn doping up to 0.5at%, while at a higher doping concentration the disorder produced in the lattice causes an increase in resistivity of the films. Exposure of LPG decreases the resistance of undoped and doped films. The response of the film is measured for both ZnO and ZnO:Sn films at different operating temperature (275-400℃) and concentration (vol %) of LPG in air. It is observed that Sn-doped ZnO films are more sensitive to LPG than undoped ZnO film. In this work, maximum response (~88 %) is observed for 0.5at % ZnO:Sn film for 1 vol% of LPG in air at 300℃. Further all the films have shown faster response and recovery times at higher operating temperatures |
| Keywords: ZnO:Sn, thin film, spray pyrolysis, LPG sensor |
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FIGURES |
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Fig.1
XRD patterns of the typical Sn-doped ZnO thin films |
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Fig.2
Transmission spectra of undoped and Sn-doped ZnO thin films. |
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Fig.3
Absorbance spectra of undoped and Sn-doped ZnO thin films |
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Fig.4
Plots of (αhv)2 vs hv for different Sn-doped ZnO thin films. |
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Fig.5
TEM images of Sn-doped ZnO samples |
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Fig.6
Plot of resistivity of Sn- doped ZnO thin films as a function of temperature. The heating rate is 5 K min-1 |
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Fig.7
Sensing characteristics of the Sn-doped ZnO thin films as a function of operating temperature to different concentrations of LPG in air. |
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Fig.8
Sensing characteristics of 0.5at% Sn-doped ZnO as a function of LPG concentration in air at various operating temperatures. |
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Fig.9
Transient response characteristics of the 0.5 at% Sn-doped ZnO film to LPG at operating temperatures of 300 0C and 400 0C. |
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TABLES |
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Table.1
Process parameters for the deposition of the films |
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Table.2
Crystallite size of Sn-doped ZnO samples from TEM studies |
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