Gu. Sumanasekera et al., Effects of gas adsorption and collisions on electrical transport in single-walled carbon nanotubes, PHYS REV L, 85(5), 2000, pp. 1096-1099
Degassing of bundles of single-walled carbon nanotubes in vacuum at 500 K i
s found to drive the thermoelectricpower (TEP) strongly negative, indicatin
g that the degassed metallic tubes in a bundle are n type. The magnitude of
the negative TEP indicates that important asymmetry in the electronic carb
on pi bands exists near the Fermi energy. Easily measurable increases in th
e TEP (similar to 5-19 mu V/K) and resistivity (2%-10%) are observed at 500
K upon exposure to N-2 and He, suggesting that even gas collisions with th
e nanotube wall can contribute significantly to the transport properties.