Abstract
Abstract Highly stable and sensitive detection of trace level (approximately 1 ppm) of NH3 gas at room temperature is demonstrated for single wall carbon nanotube (SWCNT)-based resistive sensor. The sensor device was comprised of two planer Au electrodes deposited on carbon nanotubes (CNTs) by thermal evaporation method followed by patterning with photolithography process. For the growth of high-quality SWCNTs, multiple catalysts were deposited by co-sputtering method, and the yielded CNTs were in the diameter range of 0.8 to 1.5 nm. The CNTs were characterized by various techniques including Raman spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. As-grown SWCNTs-based resistive sensor showed an excellent variation in sensor response in the trace sensing range from 1 to 50 ppm of NH3 where the sensor response linearly increased with NH3 concentration. The sensing mechanism was attributed to the electron transfer to the SWCNTs as a result of NH3 oxidation on the nanotube surface. The sensor was found to have good sensitivity with a response time of a few minutes at room temperature. Sensor recovery posed a great problem at room temperature, and the fast and complete recovery was successfully achieved by using appropriate thermal treatment protocol.
Highlights
Carbon nanotubes (CNTs) are one-dimensional (1-D) nanoscale structures based on grapheme sheet and exhibit extraordinary material properties ranging from mechanical to electronic device properties [1,2]
The single wall carbon nanotube (SWCNT) film is synthesized by using self-designed thermal chemical vapor deposition (CVD) method
Sensor design and development details The sensing area comprising SWCNTs was grown by thermal CVD system on SiO2/Si substrate, and the electrode made of gold pattern structure with 60-μm channel length was fabricated by standard photolithography technique
Summary
Carbon nanotubes (CNTs) are one-dimensional (1-D) nanoscale structures based on grapheme sheet and exhibit extraordinary material properties ranging from mechanical to electronic device properties [1,2]. There are large number of reports available in the literature on sensing of chemical gas [4,5] and biological species [6,7,8] by CNT-based sensors employing various techniques. Both pristine and modified CNTs have been used in these cases where pristine CNTs have shown more intrinsic properties of the CNT materials and demonstrated high sensitivity but failed on selectivity [9]. That the characteristic device properties are independent of types of Mishra et al International Nano Letters ,2: 013, 3:46 http:///wwwwww..inl-journal..ccoomm//ccoonntteenntt///3//1/46
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