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Fullerene And Stacked Graphene The Study Of The Theory Of The Electron Transport Properties Of Molecular Devices

Posted on:2013-04-23Degree:MasterType:Thesis
Country:ChinaCandidate:S T JiaFull Text:PDF
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Using density functional theory and nonequilibrium Green’s functions method, we studied the electronic structures and transport properties of fullerene and graphene nanoribbon.Firstly, the transport properties of fullerene C82with boron/nitrogen doping is investigated. It is found that the electron transport properties of doped C82molecular devices have been enlarged and the negative differential resistance behavior can be observed. Our results shown that the distribution of electronic wave function was changed with the bias increasing. Moreover, the coupling effects of molecule and electrodes should be changed nonlinearly, and the negative differential resistance behavior have been found.Secondly, the effects of edge-hydrogenation on the electronic transport propeties of AB-stacking bilayer graphene nanoribbons (BGNRs) is studied. It is found that the transport property of bilayer graphene nanoribbons is strongly dependent on the location of hydrogenation. Especially, the transport is significantly changed for the BGNRs, which connected with electrodes and saturated by two hydrogen for each edge carbon atom.Finally, the effect of multi-vacancies defects on the electronic structures and transport propeties of AB-stacking bilayer graphene nanoribbons is studied.It is found that the energe gap of the system changes due to the multi-vacancies defects. The energe gap is increased evidently when these defects are in the edge position of the nanostrip. But when these defects are at the central of the strip, the change of the energe gap is not obvious. The edge multi-vacancies also have a greater influnce on the transport properties than the central multi-vacancies, which significantly enhanced the current. The result shows that, the reasons for the enhanced transport properties of the system are:(1)the baffle effect which is formed by the additional layer(graphite surface) is weaken by the damage of the edge structure.(2)the density of states at Fermi level is increased.
Keywords/Search Tags:carbon-based nano-materials, fulleren, graphenenanoribbons, doping, defect
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