Gas sensing characteristics of ZnO nanowires fabricated by carbothermal evaporation method

Zinc Oxide nanowires were synthesized on the Si substrate using carbothermal evaporation of ZnO+C at elevated temperatures. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy Dispersive X-ray (EDAX) methods. Resistive gas sensor was fabricated by providing ohmic contacts and micro-heater to the sample. The gas detection response of the fabricated sensor was obtained for different concentrations of methanol and ethanol vapors at different temperatures. In comparison with other resistive sensors, this sensor demonstrated higher response, and its maximum response occurred at lower operating temperature. By recording the response variations as a function of temperature, at different gas concentrations, it was demonstrated for the first time that by increasing the gas concentration, the maximum response of the device shifted to lower temperatures. Investigating the response variations in the equal gas concentrations showed that the response to ethanol, as compared to methanol, was five times higher. © 2012 IFSA.