title: The BN-pair impurity in carbon nanotubes and the possibility for disorder-induced frustration of gap formation.
abstract: We study the BN-pair impurity complex inside a metallic and a semiconducting single-walled carbon nanotube host. For the single impurity in the semiconducting tube, we find that no electron or hole bound states can be sustained because the distance between the B and the N is less than the effective Fermi-Teller radius for that system. If the BN pairs are incorporated at stoichiometric concentrations (BC(10)N nanotubes), achievable for example with a borabenzene-pyridine adduct C(10)H(10)BN precursor, the metallic tube becomes semiconducting for an ordered arrangement of the impurities, but the introduction of disorder restores a finite density of states at the Fermi level. Thus, in the mechanism presented here, disorder effectively restores the symmetry of the nanotube, returning the nanotube to its original metallic character.
authors.affiliation: Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia, Spain.
authors.forename: X
authors.initials: X
authors.lastname: Cartoixà
authors.forename: R
authors.initials: R
authors.lastname: Rurali