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Containing the electrical properties of topological defects in carbon nanotubes

Author: ZhangLiFang
Tutor: HuHuiFang
School: Central South University
Course: Condensed Matter Physics
Keywords: carbon nanotube topological defect heterojuction electron-electron correlation charge density density of states
CLC: TB383
Type: Master's thesis
Year: 2004
Downloads: 122
Quote: 1
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Abstract


As a new one-dimension nanomaterial ,Carbon nanotube have attracted great attention since their discoveries in 1991.The sensitivity of their electronic property to their geometry makes nanotube useful in many potential application., especially in nanoelecteonic devices. In this paper, we mainly study the electronic property of carbon nanotube which contain topological defects, pentagon-heptagon pairs(5/7).In this paper, using the extended Su-Schriffer-Heeger(SSH) model, we investigate the features of energetics and electronic properties of various ’junctions’ which are achieved by introducing different arrange and distribution of topological defects, pentagon-heptagon pairs(5/7) , in the perfect hexagonal network of the zigzag carbon nanotubes configuration in the real space. We calculate the electronic structure and the densities of states of three system,(9,0)-(8,0),(9,0)-(7,0)and (9,0)-(6,0), and other two system (9,0)-(9,0) and (8,0)-(8,0) . On this base , considering electron-electron correlation, furthermore we investigate the effects of electron-electron correlation on electrical properties of carbon nanotube. In addition, containing next-nearest-neighboring hopping interactions, we study the energy band and density of states of zigzag carbon nanotube, (9,0),(10,0), in reciprocal space .The result show that these topological defects are not only responsible for a change in nanotube diameter, but also for the electronic behavior in the vicinity to Fermi level .The effect of different arrangement of pentagon-heptagon pairs on the properties of carbon nanotube is remarkable. In addition, electron-electron interaction make the whole energy band move to the direction of high energy , with the increase of Coulomb interaction, the energy is broader gradually ,while the variation of energy gap depends mainly on U and V; Coulomb interaction V causes the inhomogeneous distribution of charge density, Fermi energy shift to high energy position and new Localized states appears. Finally, we study the effects of next-nearest-neighboring hopping interactions on the electronic properties of zigzag carbon nanotubes,(9,0)and (10,0), in reciprocal space. It is found that thedegeneracy is invariable and each level shifts up and down which lead to the whole band width broadening, especially ,for (9,0),the energy gap appears, and the gap of (9,0)and(10,0) change according to t .This facts imply that topological defects ,electron-electron interactions, and next-nearest-neighboring hopping interactions would play an important role in the electronic properties of carbon nanotube.

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