Self-assembly pyrolytic routes to arrays of aligned CNx nanotubes are described. The electronic properties and the density of states (DOS) of these N doped tubes characterized by scanning tunneling spectroscopy (STS) are also presented. Using tight-binding calculations, we confirm that the presence of N is responsible for introducing donor states near the Fermi Level. Finally, it will be shown that high electron irradiation during annealing at 700-800degreesC, is capable of coalescing single-walled nanotubes (SWNTs). We investigate the merge at the atomic level using tight-binding molecular dynamics (TBMD). Vacancies induce the coalescence via a zipper-like mechanism, responsible of a continuous reorganization of atoms on individual tube lattices within the adjacent tubes. The latter results pave the way to the fabrication of nanotube contacts, nanocircuits and strong 3D composites using irradiation doses under annealing conditions.
