Authors
Abstract
In this study, tungsten oxide nanorods have been grown by thermal oxidation of tungsten film deposited on oxidized silicon substrates for gas sensing applications. Tungsten film of thickness 100 nm was deposited by sputtering method and thermally oxidized in atmospheric ambient to synthesize nanorods. The morphology and crystal structure of tungsten oxide nanorods were characterized by scanning electron microscopy and X-ray diffraction. Also, crystal structure was verified using Raman techniques. Surface chemical composition of nanorods was analyzed using X-ray photoelectron spectroscopy. Results revealed that 100 nm film of tungsten, oxidized at 450 oC, produces nanorods of WO3 having monoclinic structure with diameter ~100 nm and length up to 1µm. Using standard photolithography process, Au/Cr inter digital electrodes were formed and nanorods were synthesized on it for VOCs sensing application. Sensor incorporating WO3 nanorods exhibits very good response to ethanol, methanol and acetone vapors. The sensor response was studied at different operating temperatures for varying concentration of VOCs. The results suggest the sensor has good potential towards gas sensing applications. It is demonstrated that these sensors can detect upto 10 ppm of ethanol vapour concentration when operated at 100 oC temperature.
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