Calculating thermopower due to fluctuation-assisted tunnelling with application to carbon nanotube ropes
✍ Scribed by G.C. McIntosh; A.B. Kaiser
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 98 KB
- Volume
- 1
- Category
- Article
- ISSN
- 1567-1739
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✦ Synopsis
We show how Sheng's theory of ¯uctuation-assisted tunnelling can be used to calculate thermopower due to the presence of quantum mechanical tunnelling barriers. For a hole-like situation, this calculated thermopower behaviour increases approximately linearly with increasing temperature (commencing from zero in the zero temperature limit) until a knee is reached, after which the thermopower continues to increase linearly but with a reduced slope. In Sheng's theory, the amplitude for the barrier ¯uctuations increases with increasing temperature and the knee occurs when the thermal ¯uctuations become comparable to the magnitude of the tunnelling barriers. Interestingly, this thermopower behaviour compares quite favourably with that measured for systems of metallic single-walled carbon nanotubes (SWCNs) and, in particular, the knee seen in the temperature dependence of the carbon nanotube thermopower data at T $ 100 K arises naturally in our calculation. For a system of carbon nanotubes, tunnelling barriers could occur either between individual carbon nanotubes or else due to defects within the carbon nanotubes.