A Study On The Fabrication And Characterization Of Sputtered Cr Doped Zno Thin Film Gas Sensors

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dc.contributor.authoral-Hardan, Naif Hammad Misshin
dc.date.accessioned2018-08-08T01:02:45Z
dc.date.available2018-08-08T01:02:45Z
dc.date.issued2011-06
dc.description.abstractZinc oxide (ZnO) and chromium (Cr) doped ZnO thin films were successfully produced by reactive radio frequency co-sputtering of high purity zinc and chromium metal targets. The Cr concentrations were in the range of (1 – 4) atomic percentage. The X – ray diffraction revealed that the ZnO films possessed a polycrystalline structure with a (002) dominant phase grown along the c-axis of the hexagonal structure of the ZnO. The (002) peak was slightly shifted toward higher Bragg angles when the Cr substitutionally replaced the Zn in the ZnO crystals. The films exhibited a uniformly distributed nano grains with a columnar structure. Gas sensors based on the undoped and Cr doped ZnO films were fabricated that incorporated platinum/tantalum as electrodes and heating element. The characteristics and performance of the gas sensors were measured and evaluated through current – voltage, resistance – time response and impedance spectroscopy measurements under different gas environment oxygen, hydrogen and volatile organic compound such as acetone, ethanol and isopropanol. The gas sensor based on Cr doped ZnO exhibited higher response at lower operating temperature (250 oC and 300 oC for oxygen and VOC vapors respectively) as compared to that of the undoped ( the operating temperatures were 350 oC and 400 oC for oxygen and VOC vapors respectively). The result was explained and discussed in relation to the gas sensor’s surface structure and its subsequent effect on the sensor’s performance. Impedance spectroscopy of the sensor revealed that the sensor’s response was attributed to the grain boundary’s resistance which again suggests the significance of the sensor’s surface reactivity in the gas sensing. Finally, the sensors showed a good stability with reproducible performance in different gas concentration. The Cr doped ZnO gas sensor exhibited a higher response and faster response time as compared to that of the undoped ZnO gas sensor.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/6235
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectGas sensors based on the undopeden_US
dc.subjectCr doped ZnO films were fabricateden_US
dc.titleA Study On The Fabrication And Characterization Of Sputtered Cr Doped Zno Thin Film Gas Sensorsen_US
dc.typeThesisen_US
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