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1.
We have theoretically investigated the first correction to conductance of armchair single wall carbon nanotubes (SWCNTs) with finite length, embedded between two electrodes, due to the presence of electron–transversal phonon interaction. The perturbative scheme has been used with finite length real space nearest neighbors tight binding method. Both radial breathing and tangential modes are investigated separately. It is found that not only the conductance correction crucially depends on source-drain voltage but also it strongly depends on the length and diameter of SWCNT. So, this work opens up opportunities to control the electrical conductance of SWCNT and increases yield of micro or nanodevices based on carbon nanotube. 相似文献
2.
Low-temperature conductance of crossed carbon nanotubes with a point contact is investigated theoretically. Explicit formulas for the conductance of the device are obtained by solving the Schrödinger equation. It is shown that the conductance of each tube has minima associated with the resonance scattering of electrons at the points of contact as well with the transfer of electrons to the second tube. The electron transport between the first and the second tubes exhibits resonance behavior. 相似文献
3.
Y. Zhang M. Han 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,76(2):277-282
Using the π orbital tight-binding model and the
multi-channel Laudauer-Büttiker formula, the combined effect of
Aharonov-Bohm effect (induced by an axial magnetic field) and uniaxial
strain on quantum conductance oscillations of the electronic Fabry-Perot
resonators composed of armchair and metallic zigzag single-walled carbon
nanotubes (SWNTs) has been studied. It is found that, for the case of the
armchair SWNT, conductance oscillations near the band gap are dominated by
Aharonov-Bohm effect, while the conductance oscillations in other regions
are dominated by the uniaxial strains. The combined effect of Aharonov-Bohm
effect and uniaxial strains on quantum conductance oscillations is not
obvious. But, for the case of the metallic zigzag SWNTs, obvious
single-channel transport and one or two conductance oscillations existing in
two different gate voltage ranges were found by the combined effect of
uniaxial strain and axial magnetic field. 相似文献
4.
First-principles study for transport properties of defective carbon nanotubes with oxygen adsorption
Z. Li C.-Y. Wang S.-H. Ke W. Yang 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(3):375-382
Oxygen gas usually presents in carbon nanotube (CNT) based devices and can affect
their transport properties. Here, we perform simulations for
O2 adsorption on a (5, 5) CNT with a double vacancy. We first use
first-principles plane-wave calculation to optimize the structures
and then use single-particle Green function method to study their
transport properties. It is found that an O2 can be either
physisorbed or chemisorbed on the defective CNT. The physisorption has
only minor effects on the transport while the chemisorption can
improve it and the resulting conductance is affected by the orientation of the O2 bonding. 相似文献
5.
6.
The effect of optical phonons scattering on electronic current has been studied in metallic carbon nanotubes. The current has been calculated self-consistently by total voltage equation and the heat transport equation. The total voltage equation consists of three terms, optical phonons collision term, acoustic phonon scattering term, and contact resistance one. Including LO, A1, and E1(2) phonons in collision term, we can reproduce the experimental I-V curves displaying negative differential conductance. Furthermore, one conclusion is made that the more optical phonons are scattered by electron, the lower current is in metallic carbon nanotubes. By comparing the current under different conditions, we can make another conclusion that there should be nonequilibrium optical phonons under high bias in spite of whether the metallic nanotube is suspended or not. This result agrees well with the others [M. Lazzeri, F. Mauri, Phys. Rev. B 73 (2006) 165419]. Based on these results, we do not only explain the experiment, but also propose to design a heat-controlling electronic transistor with metallic carbon nanotubes as its channel, in which the electronic current can be controlled by optical phonons. 相似文献
7.
The role of irradiation induced defects and temperature in the conducting properties of single-walled (10, 10) carbon nanotubes has been analyzed by means of a first-principles approach. We find that divacancies modify strongly the energy dependence of the differential conductance, reducing also the number of contributing channels from two (ideal) to one. A small number of divacancies (5-9) brings up strong Anderson localization effects and a seemly universal curve for the resistance as a function of the number of defects. It is also shown that low temperatures, about 15-65 K, are enough to smooth out the fluctuations of the conductance without destroying the exponential dependence of the resistivity as a function of the tube length. 相似文献
8.
Nikolai A. Poklonski Nguyen Ngoc Hieu Sergey A. Vyrko Andrei M. Popov 《Physics letters. A》2008,372(35):5706-5711
The dependence of the interwall conductance on distance between walls and relative positions of walls are calculated at the low voltage by Bardeen method for (n,n)@(2n,2n) double-walled carbon nanotubes (DWCNTs) with n=5,6,…,10. The calculations show that interwall conductance does not depend on temperature (for T?500 K) and current-voltage characteristic is linear. The conductance decreases by 6 orders of magnitude when the interwall distance is doubled. Thus, depending on the interwall distance, DWCNTs can be used as temperature stable nanoresistors or nanocapacitors. 相似文献
9.
The quantum conductance oscillations (QCOs) of the intramolecular junction
(IMJ) composed of two single-wall carbon nanotubes (SWNTs) have been studied
by using a π-orbital only tight-binding (TB) model and a Green’s
function technique. It is found that in the IMJs in addition to the rapid
QCO frequencies corresponding to the constituent tubes there exist also
their sum frequencies. The slow QCO frequencies of the IMJ will be different
from those of its corresponding two perfect tubes if they have different
chiral angles. 相似文献
10.
The quantum conductance of the quantum dots (QDs) made of two kinds of primary carbon nanotubes (CNTs), i.e., armchair and zigzag CNTs, threaded by an axial magnetic field, has been studied by using the tight binding approximation and constant interaction model. It is found that under increasing axial magnetic field, each conductance shell of the zigzag CNT-QDs could split into two groups with each group of two peaks moving up or down, respectively. And the up- and down-moving two peaks would re-group with other two peaks, down- and up-moving, in the neighboring shell, forming a new four-peak shell, and then re-splitting, re-grouping again due to the Aharonov-Bohm effect, which is in agreement with those of experiments. But, in contrast, the conductance shells of the armchair CNT-QDs do not split by the magnetic field. Our subsequent theoretical studies show further that the above phenomena, i.e., the conductance shell-splitting, re-grouping, and re-splitting again with increasing the magnetic field exist in all the CNT-QDs except for the armchair one. 相似文献
11.
Peng Zhao Peiji Wang Zhong Zhang Changfeng Fang Yiming Wang Yaxin Zhai Desheng Liu 《Solid State Communications》2009,149(23-24):928-931
We have studied the electronic transport properties of an optical molecular switch based on the diarylethene molecule with two single-walled carbon nanotube (SWCNT) electrodes using first-principles transport calculations. It is shown that the closed form shows an overall higher conductance than the open form at low bias which is independent of the SWCNTs’ chirality. Meanwhile, the conductance of the molecular switch can be tuned by changing the chirality of the SWCNTs. 相似文献
12.
Multishell conduction in multiwalled carbon nanotubes 总被引:3,自引:0,他引:3
The full electronic complexity of multiwalled carbon nanotubes may be explored by sequentially removing individual carbon
shells. This technique is employed to directly measure the number of shells contributing to conduction at room temperature,
as well as the contribution of each shell to the overall conductance. By exploring the gate dependence of the conductance,
the random alternation between semiconducting and metallic shells can also be observed.
Received: 31 August 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献
13.
在紧束缚近似下,利用常量相互作用模型和Landauer-Bütticker公式,计算了扶手椅型和金属锯齿型碳纳米管量子点的电导。发现,根据碳纳米管量子点的长度的不同,扶手椅型碳纳米管量子点的电导可以具有两电子或四电子的壳层结构。而锯齿型碳纳米管量子点的电导却仅有四电子的壳层结构,与长度无关;这些理论结果与之前的实验结果符合的很好。 相似文献
14.
M. P. Danilaev E. A. Bogoslov Yu. E. Pol’skii A. R. Nasybullin M. S. Pudovkin A. R. Khadiev 《Technical Physics》2017,62(2):255-260
The influence of growth conditions on the carbon dendrite structure has been investigated. The threshold values of the ratio between electron temperature T e and kinetic temperature T of the gas near a needle electrode and of the discharge current density, which are necessary for dendritic growth, have been determined. It has been shown that the hexagonal structure of submicron carbon particles arises when a number of hydrocarbons are used to synthesize dendrites. It has been found that the degree of order in the carbon structure can be controlled by applying external actions at the stage of graphite particle nucleation. The characteristic frequencies of inertial actions that may be energetically appropriate must exceed 10 kHz. 相似文献
15.
《Current Applied Physics》2002,2(6):497-501
Chemical modification has been performed on purified single walled carbon nanotubes. XPS spectrum shows that the peak corresponding to C (1s) centered at 284.38 eV in pure nanotubes (graphitic C) is 0.4 eV downshifted in chlorinated sample. Subsequent coupling reactions were carried out with diamine molecules to form intertube connections. Tripropylentetramine and phenylendiamine have been chosen as a molecular linker. End-to-side and end-to-end nanotube interconnections are formed and then observed by atomic force microscopy (AFM). Statistical analysis made from AFM images shows around 30% junctions in functionalized and less than 2% in pristine material. Remarkable features can be observed in the Raman spectra at different functionalization steps. Simple conductance measurements on bucky papers prepared from prestine nanotubes and from nanotubes modified at various steps have been made and are discussed. 相似文献
16.
T. Mihara K. Miyamoto M. Kida T. Sasaki N. Aoki Y. Ochiai 《Superlattices and Microstructures》2003,34(3-6):383
A multiwall carbon nanotube crossroads has been fabricated by a manipulation technique using a glass microcapillary, and the low temperature transport properties investigated. The two-terminal conductance of an individual tube shows Tomonaga–Luttinger liquid behavior G∝Tα at high temperature and dI/dV ∝V α at low temperature. However, no evidence of such a power-law behavior is obtained in the four-terminal conductance at the junction, where the conductance shows an almost metallic behavior ‘corrected’ by weak localization. Weak localization would essentially appear in electron states at the junctions of MWNTs. 相似文献
17.
A method of surface curvature of carbon nanotubes has been proposed for quantitative estimation of the longitudinal conductivity of nanotubes. A dispersion relation for the electron spectrum of single-walled carbon nanotubes has been obtained analytically. The change in the zone structure of nanotubes of various types and diameters caused by taking into account the surface curvature has been analyzed. The temperature dependence of the longitudinal component of conductivity with allowance for the surface curvature for a series of nanotubes has been calculated. The comparison with the conductivity of a plane graphene has been performed. It has been shown that, in zig-zag tubes, the correction of the conductivity for the surface curvature decreases with an increase in temperature as well as with an increase in the radius of curvature. 相似文献
18.
V. R. Galakhov S. N. Shamin E. M. Mironova M. A. Uimin A. Ye. Yermakov D. W. Boukhvalov 《JETP Letters》2013,96(11):710-713
The electronic structure of carbon shells of carbon encapsulated iron nanoparticles carbon encapsulated Fe@C has been studied by X-ray resonant emission and X-ray absorption spectroscopy. The recorded spectra have been compared to the density functional calculations of the electronic structure of graphene. It has been shown that an Fe@C carbon shell can be represented in the form of several graphene layers with Stone-Wales defects. The dispersion of energy bands of Fe@C has been examined using the measured C Kα resonant X-ray emission spectra. 相似文献
19.
We identify a class of covalent functionalizations that preserve or control the conductance of single-walled metallic carbon nanotubes. [2+1] cycloadditions can induce bond cleaving between adjacent sidewall carbons, recovering in the process the sp;{2} hybridization and the ideal conductance of the pristine tubes. This is radically at variance with the damage permanently induced by other common ligands, where a single covalent bond is formed with a sidewall carbon. Chirality, curvature, and chemistry determine bond cleaving, and in turn the electrical transport properties of a functionalized tube. A well-defined range of diameters can be found for which certain addends exhibit a bistable state, where the opening or closing of the sidewall bond, accompanied by a switch in the conductance, could be directed with chemical, optical, or thermal means. 相似文献
20.
Peng Zhao Chang-feng Fang Yi-ming Wang Ya-xi Zhai De-sheng Liu 《Current Applied Physics》2009,9(6):1213-1216
We have studied the switching characteristics of an optical molecular switch based on the 15,16-dinitrile dihydropyrene/cyclophanediene (DDP/CPD) molecule with two single-walled carbon nanotube (SWCNT) electrodes using first-principles transport calculations. It is shown that the DDP shows an overall higher conductance than the CPD at low bias which is independently of the SWCNT chirality. Meantime, the conductance of the molecular switch can be tuned by the chirality of the SWCNT. 相似文献