The Study Of Transport Properties Of Doped Chains And Nanoribbons With Antidot Arrays

Impurities and defects are unavoidable in the preparing of nanomaterials,however, in order to improve their performance, people have to dope and make kindsof defects in a certain way. In the following, we investigate three kinds of nanosystem:the doped chains, graphene nanoribbons with antidote arrays and graphenenanoribbons doped with BN, our results are summarized as follows:1. We quantitatively study the quantum diffusion in a bilateral doped chain,which is randomly doped on both sides. Three electronic characteristics calculated:autocorrelation function C(t), the mean square displacement d(t) and the participationnumber P(E) in different doping situations. The results show that the quantumdiffusion is more sensitive to the small ratio of doping, there exists a critical dopingratio q0, and C(t), d(t) and P(E) have different variation trends on different sides of q0.For the self-doped chain, the doped atoms have tremendous influence on the centralstates of P(E), which causes the electronic states distributed in other energy bands toaggregate to the central band (E=0) and form quasi-mobility edges there. All of thedoped systems experience an incomplete transition of metal-semiconductor-metal.2. We calculated the transport properties of graphene nanoribbon with antidotarrays, which is penetrated by one or more rectangle nanoholes. Emphasis is put onanalyzing the electronic conductance, density of states and local density of states inthis system. As the results show, these rectangle nanoholes bring in several localizedstates, the conductance vibrated irregularly near the femi-energy. The conductance isheavily dependent on the position and size of the nanohole: when the nanohole is sitin the centre of the nanoribbon and has a small width(W<4), the change of theconductance near feimi-energy can almost be neglected; while the position is nearerthe edge of the nanoribbon or its width becomes bigger, the electronic transport of thesystem near femi-energy becomes weaker; also, when the nanohole has a biggerlength, there will be more localized states in the lowest transport channel. Lastly, wefound in the nanohole superlattice with finite P periods, the minibands will split into(P-1) multiple bands. By control of the position, the size and the distribution ofnanoholes, we can have an effective modulation of the electronic transport propertiesof zigzag graphene nanoribbon. 3. we quantitatively study the trasport properties of zigzag graphene nanoribbonand metallic armchair graphene nanoribbon BN quantum well, electronic conductanceand density of states are mainly considered. As the result show, the BN chains wedoped linearly suppress the electronic transport in the armchair graphene nanoribbon,a platform appears in the conductance curve near the Fermi energy, the height of theplatform behaves like the inverse of the number of the BN chains; however, the BNchains brokes the edge states in the zigzag-edged nanoribbon, leading to hugeresonance peak and antiresonance valley appear near the Fermi energy. Then weconsider curving the nanoribbon and calculating the new system. Similar toarmchair-edged nanoribbon, the electronic transport suffer from a linear suppression,the conductance curve near the Fermi energy remains step-shaped, and the height ofthe step comes down lower and lower with the increasing of BN chains in the system,when the BN chains reaches to a certain number, this transport system can transformfrom metalic to semiconducting.The control of the impurities and defects is the core problem in the preparationcraft of the nanomaterial. By the calculation of the above three systems, we can havea theoretical forecast of the relative experimental phenomenon, and a good guidanceof the preparation of these kinds of nanomaterial systems.