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Investigation of the carbon monoxide gas sensing characteristics of tin oxide mixed cerium oxide thin films.

Durrani SM, Al-Kuhaili MF, Bakhtiari IA, Haider MB - Sensors (Basel) (2012)

Bottom Line: The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive.We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm.Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. smayub@kfupm.edu.sa

ABSTRACT
Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6-21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

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Response of the SnO2 mixed CeO2 thin film sensor to different CO concentrations. The film thickness was 220 nm and temperature of 430 °C.
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f8-sensors-12-02598: Response of the SnO2 mixed CeO2 thin film sensor to different CO concentrations. The film thickness was 220 nm and temperature of 430 °C.

Mentions: Similar results were observed for other temperatures in the range 300–500 °C. Therefore, from these findings, the bias voltage was fixed at 1.5 V for subsequent experimental work. The effect of biasing voltages has been discussed in detail [10,26,27]. Briefly the effect of applied biasing voltage perhaps could be visualized as following; the applied biasing voltage would increase/decrease the Schottky barrier height (created by O− adsorption), which in turn would increase/decrease the threshold CO concentration for the p-n or vice versa transitions. Figure 7 shows the sensitivity variation as a function of operating temperature (in the range 300 °C to 500 °C) for SnO2 mixed CeO2 film of thickness 220 nm and CO concentrations of 500 ppm. The inset of Figure 7 shows the peak value of the sensitivity for SnO2 mixed CeO2 is 430 °C. For the optimum operating temperatures 430 °C, the dependence of sensitivity on CO gas concentration was also investigated. The results are given in Figure 8, which shows that the sensor was capable of detecting CO gas concentrations as low as 5 ppm. It is clearly evident from Figures 7 and 8 that the SnO2 mixed CeO2 thin film gas sensor was highly sensitive to CO.


Investigation of the carbon monoxide gas sensing characteristics of tin oxide mixed cerium oxide thin films.

Durrani SM, Al-Kuhaili MF, Bakhtiari IA, Haider MB - Sensors (Basel) (2012)

Response of the SnO2 mixed CeO2 thin film sensor to different CO concentrations. The film thickness was 220 nm and temperature of 430 °C.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376601&req=5

f8-sensors-12-02598: Response of the SnO2 mixed CeO2 thin film sensor to different CO concentrations. The film thickness was 220 nm and temperature of 430 °C.
Mentions: Similar results were observed for other temperatures in the range 300–500 °C. Therefore, from these findings, the bias voltage was fixed at 1.5 V for subsequent experimental work. The effect of biasing voltages has been discussed in detail [10,26,27]. Briefly the effect of applied biasing voltage perhaps could be visualized as following; the applied biasing voltage would increase/decrease the Schottky barrier height (created by O− adsorption), which in turn would increase/decrease the threshold CO concentration for the p-n or vice versa transitions. Figure 7 shows the sensitivity variation as a function of operating temperature (in the range 300 °C to 500 °C) for SnO2 mixed CeO2 film of thickness 220 nm and CO concentrations of 500 ppm. The inset of Figure 7 shows the peak value of the sensitivity for SnO2 mixed CeO2 is 430 °C. For the optimum operating temperatures 430 °C, the dependence of sensitivity on CO gas concentration was also investigated. The results are given in Figure 8, which shows that the sensor was capable of detecting CO gas concentrations as low as 5 ppm. It is clearly evident from Figures 7 and 8 that the SnO2 mixed CeO2 thin film gas sensor was highly sensitive to CO.

Bottom Line: The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive.We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm.Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. smayub@kfupm.edu.sa

ABSTRACT
Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6-21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

Show MeSH