Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 88: Transport: Carbon Nanotubes
TT 88.4: Talk
Thursday, March 19, 2015, 10:15–10:30, A 053
Strong localization in defective carbon nanotubes — •Fabian Teichert1,2, Andreas Zienert2, Jörg Schuster3, and Michael Schreiber1 — 1Institute of Physics, Technische Universität Chemnitz, Chemnitz, Germany — 2Center for Microtechnologies, Technische Universität Chemnitz, Chemnitz, Germany — 3Fraunhofer Institute for Electronic Nano Systems, Chemnitz, Germany
Carbon nanotubes (CNTs) are a prominent example for new materials in microelectronics, overcoming the miniaturization problem. So far CNTs cannot be grown or deposited in an ideal and reproducible way inside a device. As one consequence they contain defects.
The present work describes the transport properties of armchair CNTs with randomly positioned realistic defects, namely monovacancies and divacancies. The calculations are based on a fast, linearly scaling recursive Green's function formalism, allowing to treat large systems quantum-mechanically. The electronic structure is described by a density-functional-based tight-binding model.
The transmission spectrum of CNTs with single / many defects is studied. The influence of certain defect densities, the diameter of the CNT, and the temperature is investigated within a statistical analysis. It is shown that the system is in the regime of strong localization (i.e. Anderson localization), where the conductivity scales exponentially with the number of defects. This allows us to extract localization lengths, which depend on defect density, CNT diameter, and temperature. Finally, the correlation between the localization length and the single-defect conductance is shown.