Chemical doping of individual semiconducting carbon-nanotube ropes

Abstract

We report the effects of potassium doping on the conductance of individual semiconducting single-walled carbon nanotube ropes. We are able to control the level of doping by reversibly intercalating and de-intercalating potassium. Potassium doping changes the carriers in the ropes from holes to electrons. Typical values for the carrier density are found to be $\ensuremath{\sim}100$--1000 electrons/$\ensuremath{\mu}\mathrm{m}.$ The effective mobility for the electrons is ${\ensuremath{\mu}}_{\mathrm{eff}}\ensuremath{\sim}20$--60 ${\mathrm{cm}}^{2}{\mathrm{V}}^{\ensuremath{-}1}{\mathrm{s}}^{\ensuremath{-}1},$ a value similar to that reported for the hole effective mobility in nanotubes [R. Martel et al., Appl. Phys. Lett. 73, 2447 (1998)].