Thermoelectric Power ofp-Doped Single-Wall Carbon Nanotubes and the Role of Phonon Drag

Abstract

We measured thermoelectric power $S$ of bulk single-wall carbon nanotube materials $p$ doped with acids. In contrast to oxygen-exposed or degassed samples, $S$ is very small at the lowest temperatures, increases superlinearly above a characteristic and sample-dependent $T$, and then levels off. We attribute this unusual behavior to 1D phonon drag, in which the depression of the Fermi energy cuts off electron-phonon scattering at temperatures below a characteristic $T_0$. This idea is supported by a model calculation in which the low temperature behavior of phonon drag is specifically related to the one-dimensional character of the electronic spectrum.