A theoretical investigation of the effect of adsorbed NO2 molecules on electronic transport in semiconducting single-walled carbon nanotubes

We investigated the variation of electronic transport in a semiconducting single-walled carbon nanotube (SWCNT) due to NO2 molecules adsorbed on different locations of the SWCNT surface through a theoretical means. Our results indicate that the electronic conductance of a semiconducting SWCNT strongly depends on the distance between the electrode and the NO2 adsorption site. In some cases, the conductance variation can reach ten fold. Negative differential resistance behavior is identified in the current-voltage characteristics when a NO2 molecule is adsorbed on the surface of a semiconducting SWCNT. These phenomena originate from the interaction between the electrode and the NO2 due to the finite length of the SWCNT. A NO2 sensing mechanism of an SWCNT-based chemical sensor at low NO2 concentration was proposed. Several examples of this SWCNT-based sensor adsorbed with two NO2 molecules were used to demonstrate the complicated conductivity variation when the multiple NO2 adsorptions take place in an SWCNT-based NO2 gas sensor. (C) 2010 Elsevier Ltd. All rights reserved.