title: The role of oxygen at the interface between titanium and carbon nanotubes.
abstract: We study the interface between carbon nanotubes (CNTs) and surface-deposited titanium using electron microscopy and photoemission spectroscopy, supported by density functional calculations. Charge transfer from the Ti atoms to the nanotube and carbide formation is observed at the interface which indicates strong interaction. Nevertheless, the presence of oxygen between the Ti and the CNTs significantly weakens the Ti-CNT interaction. Ti atoms at the surface will preferentially bond to oxygenated sites. Potential sources of oxygen impurities are examined, namely oxygen from any residual atmosphere and pre-existing oxygen impurities on the nanotube surface, which we enhance through oxygen plasma surface pre-treatment. Variation in literature data concerning Ohmic contacts between Ti and carbon nanotubes is explained via sample pre-treatment and differing vacuum levels, and we suggest improved treatment routes for reliable Schottky barrier-free Ti-nanotube contact formation.
authors.affiliation: Centre de Recherche en Physique de la Matière et du Rayonnement (PMR), University of Namur, 61 rue de Bruxelles, 5000, Namur, Belgium. alexandre.felten@fundp.ac.be
authors.forename: Alexandre
authors.initials: A
authors.lastname: Felten
authors.forename: Irene
authors.initials: I
authors.lastname: Suarez-Martinez
authors.forename: Xiaoxing
authors.initials: X
authors.lastname: Ke
authors.forename: Gustaaf
authors.initials: G
authors.lastname: Van Tendeloo
authors.forename: Jacques
authors.initials: J
authors.lastname: Ghijsen
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Pireaux
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Drube
authors.forename: Carla
authors.initials: C
authors.lastname: Bittencourt
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Ewels