Abstract
The fabrication of cobalt (Co) catalyzed multi-walled carbon nanotubes (MWNTs) film sensor for the detection of carbon mono-oxide (CO) gas has been reported. Cobalt (Co) catalyzed carbon nanotubes have been synthesized on silicon oxide grown silicon substrate using low pressure chemical vapor deposition. The diameter of these multi-walled nanotubes (MWNTs) varies from 40-100 nm and the length is on the order of several tens of micrometers. To measure the gas sensing properties of this sensor, a typical pattern of gold electrodes has been thermally evaporated. The typical responses of MWCNTs gas sensor for different concentration (40, 100, 140 & 200 ppm) of sensing gas i.e. carbon mono-oxide (CO) have been studied. It is observed that this MWNTs gas sensor shows a quick response to CO gas with the fast recovery time. Temperature dependence of the resistance of this MWNTs-based film sensor has also been studied for a temperature range of 300-500K. It is found that the resistance decreases with the increase in temperature for all concentration of CO gas. The sensitivity and responsiveness has been estimated with respect to the time as well as temperature. The responsiveness increases whereas the sensitivity of this sensor decreases with the increase in temperature for all concentrations of CO gas. Some electrical parameters such as activation energy and pre-exponential factor have also been estimated to understand the electrical transport properties of this sensor.