Impedance spectroscopy of undoped and Cr-doped ZnO gas sensors under different oxygen concentrations |
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Authors: | N Al-Hardan MJ Abdullah A Abdul Aziz |
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Institution: | School of Physics, Universiti Sains Malaysia (USM), 11800 Penang, Malaysia |
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Abstract: | Thin films of undoped and chromium (Cr)-doped zinc oxide (ZnO) were synthesized by RF reactive co-sputtering for oxygen gas sensing applications. The prepared films showed a highly c-axis oriented phase with a dominant (0 0 2) peak appeared at a Bragg angle of around 34.13 °, which was lower than that of the standard reference of ZnO powder (34.42 °). The peak shifted to a slightly higher angle with Cr doping. The operating temperature of the ZnO gas sensor was around 350 °C, which shifted to around 250 °C with Cr-doping. The response of the sensor to oxygen gas was enhanced by doping ZnO with 1 at.% Cr. Impedance spectroscopy analysis showed that the resistance due to grain boundaries significantly contributed to the characteristics of the gas sensor. |
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Keywords: | Impedance spectroscopy Metal oxide sensors Oxygen gas sensor RF sputtering Zinc oxide |
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