Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription Tuning the conductance of single walled carbon nanotubes by ion irradiation in the Anderson localization regimeC. Gómez-Navarro 1 , P.J. Carbon nanotubes 1,2 are a good realization of one-dimensional crystals where basic science and potential nanodevice applications merge 3 . Defects are known to modify the electrical resistance of carbon nanotubes 4 . They can be present in asgrown carbon nanotubes, but controlling externally their density opens a path towards the tuning of the nanotube electronic characteristics. In this work consecutive Ar + irradiation doses are applied to single-walled nanotubes (SWNTs) producing a uniform density of defects. After each dose, the room temperature resistance versus SWNT-length [R(L)] along the nanotube is measured. Our data show an exponential dependence of R(L) indicating that the system is within the strong Anderson localization regime. Theoretical simulations demonstrate that mainly di-vacancies contribute to the resistance increase induced by irradiation and that just a 0.03% of di-vacancies produces an increase of three orders of magnitude in the resistance of a 400 nm SWNT length.The traditional approximation to reduce the size and enhance the performance of electronic devices may not be applicable in the near future 5 . Electronic circuits based on molecules have created great expectation for their new foresighted properties. For the case of electronic circuits based on carbon nanotubes 6 , the influence of disorder and defects 4,7 is of fundamental relevance in the performance of the device. In particular, the density of defects would determine the transport in nanotubes from a ballistic regime 8,9 to either weak or strong localization regimes. Quantum theory dictates that for a one dimensional conductor of length L 10,11 , with a given density of defects, localization effects emerge when the "phase coherence length" L φ is larger than the localization length L 0 . If L is not too large (for L about 3-10 L 0 ) and the inelastic interaction is weak, the wire resistance is controlled by the phase-coherent electron propagation 12 , falling into the strong localization regime in which the resistance increases exponentially with the length of the wire. This regime has not been observed in single-walled nanotubes in spite of the many evidences for weak localization diffusive regime and quantum interference in multiwalled carbon nanotubes 13 . By changing the density of defects, L 0 can be modified allowing to control the resistance of the one dimensional conductor.Induced defects have been already used to modify different properties of carbon nanotubes. Indeed, electron-beam has been used to create in-situ nanotube junctions 14 and to enhance the mechanical response of nanotubes bundles by creating stable links among the tubes 15...

Two-dimensional graphene, carbon nanotubes, and graphene nanoribbons represent a novel class of low dimensional materials that could serve as building blocks for future carbon-based nanoelectronics. Although these systems share a similar underlying electronic structure, whose exact details depend on confi nement effects, crucial differences emerge when disorder comes into play. In this review, we consider the transport properties of these materials, with particular emphasis on the case of graphene nanoribbons. After summarizing the electronic and transport properties of defect-free systems, we focus on the effects of a model disorder potential (Anderson-type), and illustrate how transport properties are sensitive to the underlying symmetry. We provide analytical expressions for the elastic mean free path of carbon nanotubes and graphene nanoribbons, and discuss the onset of weak and strong localization regimes, which are genuinely dependent on the transport dimensionality. We also consider the effects of edge disorder and roughness for graphene nanoribbons in relation to their armchair or zigzag orientation.