In-Situ Electric Transport of Carbon Nanotubes
Electrical transport in single-walled nanotubes (SWNTs) and multiwalled nanotubes (MWNTs) is of great importance for their applications in electronics . The electronic band structure of SWNTs is well known: depending on the helicity and statistically in a third of the cases, a tube has two one-dimensional subbands (channels) that intercept the Fermi level, giving rise to metallic conduction. More precisely, only armchair tubes are gapless: all others are often referred to as metallic, although small gaps that are introduced by curvature effects of the order of 10 meV for 1.4 nm diameter SWNTs effect transport at low temperatures. The gap diminishes with increasing tube diameter. Measurements of nanotube conductance mainly use two techniques. Using lithographically made gold electrodes, a carbon nanotube is laid down across two or four electrodes, and the I-V characteristic is measured [2, 3]. The other technique takes the advantage of using liquid mercury as a soft contacting electrode; a nanotube is inserted into the mercury, and the conductance is monitored as a function of the depth that the nanotube is inserted into the mercury . The latter has been carried out in-situ in TEM. This chapter is intended to review the progress in applying the second technique in electrical property characterization of nanotubes. A comprehensive review about all of the existing literature and the comparison of data in electrical characterization can be found from .
KeywordsCarbon Nanotubes Contact Resistance Graphitic Particle Quantum Conductance Mercury Surface
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- 1.For a review, see C. Dekker, Physics Today (May 1999) 22.Google Scholar