Nitrogen doping of metallic single-walled carbon nanotubes: n-type   conduction and dipole scattering
  The charge transport properties of individual, metallic nitrogen doped, single-walled carbon nanotubes are investigated. It is demonstrated that n-type conduction can be achieved by nitrogen doping. Evidence was obtained by appealing to electric-field effect measurements at ambient condition. The observed temperature dependencies of the zero-bias conductance indicate a disordered electron system with electric-dipole scattering, caused mainly by the pyridine-type nitrogen atoms in the honeycomb lattice. These results illustrate the possibility of creating all-metallic molecular devices, in which the charge carrier type can be controlled. 
V. Krstic, G. L. J. A. Rikken, P. Bernier, S. Roth, M. Glerup