Dependence of transport through carbon nanotubes on local Coulomb potential

In this paper, we present the results of helium temperature transport measurements through carbon nanotubes using an AFM conductive tip as a mobile gate for creation of a local distributive Coulomb potential. In semiconducting nanotubes we observe shifting of the conductance peaks with changing of the AFM tip position. This result can be explained with a particle in the box quantum model. In high quality metallic nanotubes we observe that the local Coulomb potential does not destroy the fourfold degeneracy of the energy levels.