Electronic Transport Properties of Carbon NanoBuds (original) (raw)
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Study of electronic transport mechanism in carbon nanobuds (CNBs) using first-principles approach
In the present work we have investigated the electronic transport properties of fullerene functionalized single wall carbon nanotube (14,0) i.e. the carbon nanobuds (CNBs) with two different configurations using the first-principles density functional-based non-equilibrium Green function (NEGF) method. Our findings show that the localized states developed in the vicinity of bud region cause strong back-scattering and reduce the electron transmission significantly in the entire energy region. The I-V characteristics of the pristine CNT(14,0) show that it is semiconducting in nature with a threshold voltage 0.55 V. Upon fullerene functionalization of CNT (formation of small neck carbon nanobud) the threshold voltage changes to 0.60V. However on functionalization with long neck (6,0), no noticeable change in threshold voltages is observed. It has been further ascertained from I-V characteristic plots that zigzag nanotubes upon nanobud formation do not change their semiconducting nature. CNBs are promising candidates for nano electronics as they can enhance the cold field emission due to their charge distribution profile which extends from tube to the bud region.
Electron transport and optical properties of carbon nanostructures from first principles
Computer Physics Communications, 2005
Recent developments in ab initio studies of the nonlinear electron transport and optical properties of nanostructures are discussed. As examples of applications, results are presented for carbon atomic wires and single-walled carbon nanotubes. For the carbon atomic wires, strong nonlinearities in the I -V characteristics and conductance are obtained, and the role of interface chemistry and lead composition is demonstrated to be extremely important in determining its transport properties. For singlewalled carbon nanotubes, explicit treatment of many-electron interactions shows that excitonic effects are dominant in these quasi-one dimensional systems and thus essential to explain the observed optical absorption spectra.
Electronic structure and quantum transport in carbon nanotubes
Applied Physics A: Materials Science & Processing, 1998
The electrical properties of various forms of carbon nanotubes are presented with particular emphasis placed on individual multi-wall and single-wall tubes. After a brief survey of the electronic structure of single-wall carbon nanotubes, electronic transport mechanisms are overviewed in relation with the dimensionality of the carbon system. Typical quantum aspects of low temperature electronic conduction for low dimensionality encountered in some carbon nanotubes are discussed.
Electronic properties and quantum transport in Graphene-based nanostructures
European Physical Journal B, 2009
Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) represent a novel class of low-dimensional materials. All these graphene-based nanostructures are expected to display the extraordinary electronic, thermal and mechanical properties of graphene and are thus promising candidates for a wide range of nanoscience and nanotechnology applications. In this paper, the electronic and quantum transport properties of these carbon nanomaterials are reviewed. Although these systems share the similar graphene electronic structure, confinement effects are playing a crucial role. Indeed, the lateral confinement of charge carriers could create an energy gap near the charge neutrality point, depending on the width of the ribbon, the nanotube diameter, the stacking of the carbon layers regarding the different crystallographic orientations involved. After reviewing the transport properties of defect-free systems, doping and topological defects (including edge disorder) are also proposed as tools to taylor the quantum conductance in these materials. Their unusual electronic and transport properties promote these carbon nanomaterials as promising candidates for new building blocks in a future carbon-based nanoelectronics, thus opening alternatives to present silicon-based electronics devices.
Fullerene-based molecular nanobridges: A first-principles study
Physical Review B, 2001
Building upon traditional quantum chemistry calculations, we have implemented an {\em ab-initio} method to study the electrical transport in nanocontacts. We illustrate our technique calculating the conductance of C$_{60}$ molecules connected in various ways to Al electrodes characterized at the atomic level. Central to a correct estimate of the electrical current is a precise knowledge of the local charge transfer between molecule and metal which, in turn, guarantees the correct positioning of the Fermi level with respect to the molecular orbitals. Contrary to our expectations, ballistic transport seems to occur in this system.
Journal of Physics: Condensed Matter, 2013
Core-hole induced electron excitations in fullerene molecules, and small-diameter conducting carbon nanotubes, are studied using density functional theory with minimal, split-valence, and triply-split-valence basis sets plus the generalized gradient approximation by Perdew-Burke-Ernzerhof for exchange and correlation. Finite-size computations are performed on the carbon atoms of a C 60 Bucky ball and a piece of (3, 3) armchair cylindrical network, terminated by hydrogen atoms, while periodically boundary conditions are imposed on a (3, 3) nanotube unit cell. Sudden creation of the core state is simulated by replacing a 1s electron pair, localized at a central site of the structures, with the effective pseudo-potentials of both neutral and ionized atomic carbon. Excited states are obtained from the ground-state (occupied and empty) electronic structure of the ionized systems, and their overlaps with the ground state of the neutral systems are computed. These overlaps enter Fermi's golden rule, which is corrected with lifetime and finite-temperature effects to simulate the many-electron response of the nanoobjects. A model based on the linked cluster expansion of the vacuum persistence amplitude of the neutral systems, in a parametric core-hole perturbation, is developed and found to be reasonably consistent with the density functional theory method. The simulated spectrum of the fullerene molecule is found to be in good agreement with x-ray photoemission experiments on thick C 60 films, reproducing the low energy satellites at excitation energies below 4 eV within a peak position error of ca. 0.3 eV. The nanotube spectra show some common features within the same experiments and describe well the measured x-ray photoelectron lineshape from nanotube bundles with an average diameter of 1.2 nm.
Electronic and transport properties of nanotubes
Reviews of Modern Physics, 2007
This article reviews the electronic and transport properties of carbon nanotubes. The focus is mainly theoretical, but when appropriate, the relation with experimental results is mentioned. While simple band-folding arguments will be invoked to rationalize how the metallic or semiconducting character of nanotubes is inferred from their topological structure, more sophisticated tight-binding and ab initio treatments will be introduced to discuss more subtle physical effects, such as those induced by curvature, tube-tube interactions or topological defects. The same approach will be followed for transport properties. The fundamental aspects of conduction regimes and transport length scales will be first briefly presented using simple models of disorder, with the derivation of a few analytic results concerning specific situations of short and long range static perturbations. Further, the latest developments in semi-empirical or ab initio simulations aiming at exploring the effect of realistic static scatterers (chemical impurities, adsorbed molecules, etc.) or inelastic electron-phonon interactions, will be emphasized. Finally, specific issues, going beyond the noninteracting electron model, will be addressed, including excitonic effects in optical experiments, the Coulomb blockade regime, and the Luttinger liquid, charge density waves or superconducting transitions.
Electronic transport properties of carbon nanotoroids
Nanotechnology, 2011
In this work, we study electronic transport properties of a quasi-one dimensional pure semi-conducting Zigzag Carbon Nanotube (CNT) attached to semi-infinite clean metallic Zigzag CNT leads, taking into account the influence of topological defect in junctions. This structure may behave like a field effect transistor. The calculations are based on the tight-binding model and Green's function method, in which the local density of states(LDOS) in the metallic section to semi-conducting section, and muli-channel conductance of the system are calculated in the coherent and linear response regime, numerically. Also we have introduced a circuit model for the system and investigated its current. The theoretical results obtained, can be a base, for developments in designing nano-electronic devices.
Electronic structure of defects and quantum transport in carbon nanotubes
Physica B: Condensed Matter, 2006
Understanding of the electronic structure and the electrical transport properties on the nanoscale becomes increasingly important for the development of the next-generation nanodevices. We have developed a first-principles pseudopotential method to calculate the quantum conductance as well as the self-consistent charge distributions of nanostructures and studied the electronic structure and quantum conductance of carbon nanotubes with impurities or defects. Even if the carbon nanotube is metallic instead of semiconducting, boron and nitrogen atoms create acceptor-like and donor-like states which act as scattering centers for conducting electrons. Various defect geometries such as Stone-Wales defects are considered which give rise to interesting localized states and the corresponding conductance characteristics. These localized states are in resonance with the extended states of the metallic nanotube and form quasibound states with broadened energy levels leading to novel conductance behaviors. For semiconducting carbon nanotubes, it is shown that various defects located at the junction of two different tubes can produce both shallow and deep defect levels. Theoretical predictions are closely compared with recent scanning tunneling microscopy and scanning tunneling spectroscopy data.