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

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

J. Vavro, M. C. Llaguno, J. E. Fischer, S. Ramesh, R. K. Saini, L. M. Ericson, V. A. Davis, R. H. Hauge, M. Pasquali, and R. E. Smalley

Phys. Rev. Lett. 90, 065503 – Published 14 February 2003

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.