Effects of gas adsorption and collisions on electrical transport in single-walled carbon nanotubes
Degassing of bundles of single-walled carbon nanotubes in vacuum at 500 K is found to drive the thermoelectricpower (TEP) strongly negative, indicating that the degassed metallic tubes in a bundle are n type. The magnitude of the negative TEP indicates that important asymmetry in the electronic carbon pi bands exists near the Fermi energy. Easily measurable increases in the TEP ( approximately 5-10 &mgr;V/K) and resistivity ( 2%-10%) are observed at 500 K upon exposure to N2 and He, suggesting that even gas collisions with the nanotube wall can contribute significantly to the transport properties.
Sumanasekera
GU
Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Adu
CK
Fang
S
Eklund
PC