Abstract
Multi-walled carbon nanotubes (MWCNTs) grown on SiO2/Si substrate, were investigated as resistive sensors for Ammonia (NH3 gas detection upto 100 ppm concentration in the presence of dry carrier gas N2. Sensitivity and recovery time are serious problem in case of NH3 sensing and these are related to the interaction mechanism between NH3 molecules and CNTs surface and the defect level of CNT. It was found that the chemisorption of NH3 molecules on the side-wall defect sites of CNTs enhances the sensitivity along with a poor recovery. We have demonstrated by an effective approach to get improved sensitivity and fast recovery. Best sensor performance and desorption of NH3 were done by tuning the DC excitation electric field applied across the sensor electrodes. Such stimulation process provides sufficient energy to the electrons to jump through defective sites due to Poole-Frenkel effect resulting in the desorption of gas.
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