Localised and delocalized charge transport in single-wall carbon-nanotube mats

We measured the complex dielectric constant in mats of single-wall carbon nanotubes between 2.7 K and 300 K up to 0.5 THz. The data are well understood in a Drude approach with a negligible temperature dependence of the plasma frequency omega(p) and scattering time tau with an additional contribution of localized charges. The dielectric properties resemble those of the best metallic polypyrroles and polyanilines. The absence of metallic islands makes the mats a relevant piece in the puzzle of the interpretation of tau and omega(p) in these polymers.