Sensitivity of nanotube chemical sensors at the onset of Poole-Frenkel conduction

We find that the applied electric field has an unexpectedly large effect on the sensitivity of a sensor consisting of a network array of carbon nanotubes. The sensors are insensitive to gas adsorption at low applied voltages and remains low until a critical potential is reached. The sensor response then rapidly increases over a small range of voltage. The critical voltage roughly corresponds to the barrier for electron hopping between defect sites. These results show that there is a correlation between the conduction mechanism in the nanotube and the sensitivity of the nanotube. Such a correlation has not been observed previously. (C) 2010 American Institute of Physics. [doi:10.1063/1.3379291]