  We report on the temperature dependence of the intrinsic resistance of long
individual disordered single-wall carbon nanotubes. The resistance grows
dramatically as the temperature is reduced, and the functional form is
consistent with an activated behavior. These results are described by Coulomb
blockade along a series of quantum dots. We occasionally observe a kink in the
activated behavior that reflects the change of the activation energy as the
temperature range is changed. This is attributed to charge hopping events
between non-adjacent quantum dots, which is possible through cotunneling
processes.
