Publication

Abstract : pThis paper reports the computational modeling and simulation of 'Multi walled carbon nanotube' (MWCNT) to characterize the adsorption of gases. The computational results were properly evaluated experimentally. CNT is known to undergo electrical breakdown on exposure to gases. This unique property has been used in designing CNT-based gas sensors. The electrical resistance of 'large diameter MWCNT' was found to decrease in the presence of air after experiencing electrical breakdown, while 'pristine MWCNTs' were not found to be appreciably sensitive. The deformation and the corresponding mechano electric effects of CNT have been well predicted. Composite electric field guided assembly (CEGA) method was used to locate a single MWCNT between electrodes. The electrical characteristics of the deposited MWCNTs were observed using I-V-curves. The large-diameter MWCNT showed better sensitivity as they possess more distorted shells that can create more adsorption sites for oxygen molecules. The oxidation of CNT begins in the defective or distorted region of the tube separated from the electrodes. The removal of complete shells including the contacts with the electrodes is observed as spikes in the I-V Graph plotted from experimental results. This observation can be due to the presence of two barriers for conductivity along the partially burnt or oxidized MWCNT, the Schottky barrier for carrier injection from the electrodes to the nanotubes and the barrier caused due to the hopping process. © 2010 American Institute of Physics./p