Superlattice properties of carbon nanotubes in a transverse electric   field
  Electron motion in a (n,1) carbon nanotube is shown to correspond to a de Broglie wave propagating along a helical line on the nanotube wall. This helical motion leads to periodicity of the electron potential energy in the presence of an electric field normal to the nanotube axis. The period of this potential is proportional to the nanotube radius and is greater than the interatomic distance in the nanotube. As a result, the behavior of an electron in a (n,1) nanotube subject to a transverse electric field is similar to that in a semiconductor superlattice. In particular, Bragg scattering of electrons from the long-range periodic potential results in the opening of gaps in the energy spectrum of the nanotube. Modification of the bandstructure is shown to be significant for experimentally attainable electric fields, which raises the possibility of applying this effect to novel nanoelectronic devices. 
O. V. Kibis, D. G. W. Parfitt and M. E. Portnoi