Localized 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.