Room temperature carrier transport through large diameter bundles of semiconducting single-walled carbon nanotube

In this work, we purify semiconducting SWNTs (S-SWNTs) using the density gradient method being already developed and compare carrier transport in dielectrophoretically formed bundles at 298 K to unseparated counterparts. We find that for a 36-nm-diameter S-SWNTs bundle produced in this work, resistance values ranging 0.4–1.6 MΩ are consistent with previously reported values for smaller diameter bundles (3 nm), where it was assumed that only the circumferential SWNT contributes to conduction from the electrode. Estimated transmission probabilities of 0.004 and 0.017, which are calculated in this work, are approximately 1–2 orders of magnitude lower than single nanotube counterparts, suggesting a significant amount of carrier scatterings in the bundled state. This is also reflected in the corresponding room temperature mean free paths of 18.6 and 4.3 nm, respectively, which are comparable to Ar+ ion damaged bundles of smaller size. We note that theses values are consistent with a value of 22 nm predicted from a semi-classical transport model for the elastic scattering length for carriers in an idealized (6, 5) SWNT.