Thin transparent carbon nanotube networks:: effects of ion irradiation

We investigate the effect of irradiation by Ar+ and N+ ions on the properties of thin transparent networks of single-wall carbon nanotubes (SWNTs). The irradiation produces a small reduction in the infra-red transmittance of the networks at a wavelength of 2000 nm that correlates with the much larger reduction in conductance, and the peaks in the infra-red-visible absorbance spectrum are strongly reduced. Ion irradiation greatly increases the localization of the charge carriers, suppressing the conductance at low temperatures more severely than at room temperature. The conductance follows variable-range hopping behaviour for all samples. Nonlinearity in the current-voltage characteristics of the thin SWNT networks is observed only at very low temperatures. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.