Tight-Binding Approximation Calculation on the Electronic Structure of Graphene and Graphene Nanoribbons

2013 ◽  
Vol 341-342 ◽  
pp. 199-203 ◽  
Author(s):  
Hong Xia Wang ◽  
Cheng Lai Yang ◽  
You Zhang Zhu ◽  
Ni Chen Yang
Keyword(s):  
Electronic Structure ◽  
Energy Gap ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Periodic Boundary Conditions ◽  
Tight Binding Approximation ◽  
Width Direction ◽  
Armchair Graphene Nanoribbons ◽  
Approximation Calculation ◽  
Armchair Graphene

The electronic structure expression of graphene was derived using tight-binding approxi-mation method. According to periodic boundary conditions in width direction of graphene nanorib-bons wave vector, the electronic structure analytical expression of armchair graphene nanoribbons was deduced, and the energy band curve were given. The conditions of graphene nanoribbons being metal or semiconductor were obtained. The results show that when nanoribbons width meetsL=3na/2, the energy gap is zero and armchair graphene nanoribbons behave as the metallic. With the increase of the nanoribbons width, the energy gap of semiconducting nanoribbons decreases. The electronic properties of graphene nanoribbons are closely related to their geometry. The graphene nanoribbons can be modulated into metal or semiconductor with different band gap by controlling their width.

scholarly journals Intrinsic Spin-Orbit Coupling in Zigzag and Armchair Graphene Nanoribbons

2011 ◽  
Vol 2011 ◽  
pp. 1-7
Author(s):  
Ying Li ◽  
Erhu Zhang ◽  
Baihua Gong ◽  
Shengli Zhang
Keyword(s):  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Geometrical Parameters ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Binding Model ◽  
Tight Binding Approximation ◽  
Energy Gaps ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

Starting from a tight-binding model, we derive the energy gaps induced by intrinsic spin-orbit (ISO) coupling in the low-energy band structures of graphene nanoribbons. The armchair graphene nanoribbons may be either semiconducting or metallic, depending on their widths in the absence of ISO interactions. For the metallic ones, the gaps induced by ISO coupling decrease with increasing ribbon widths. For the ISO interactions, we find that zigzag graphene nanoribbons with odd chains still have no band gaps while those with even chains have gaps with a monotonic decreasing dependence on the widths. First-principles calculations have also been carried out, verifying the results of the tight-binding approximation. Our paper reveals that the ISO interaction of graphene nanoribbons is governed by their geometrical parameters.

scholarly journals Unified Drain Current Model of Armchair Graphene Nanoribbons with Uniaxial Strain and Quantum Effect

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
EngSiew Kang ◽  
Razali Ismail
Keyword(s):  
Quantum Confinement ◽  
Graphene Nanoribbons ◽  
Quantum Effect ◽  
Current Model ◽  
Tight Binding ◽  
Drain Current ◽  
Published Data ◽  
Tight Binding Approximation ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

A unified current-voltageI-Vmodel of uniaxial strained armchair graphene nanoribbons (AGNRs) incorporating quantum confinement effects is presented in this paper. TheI-Vmodel is enhanced by integrating both linear and saturation regions into a unified and precise model of AGNRs. The derivation originates from energy dispersion throughout the entire Brillouin zone of uniaxial strained AGNRs based on the tight-binding approximation. Our results reveal the modification of the energy band gap, carrier density, and drain current upon strain. The effects of quantum confinement were investigated in terms of the quantum capacitance calculated from the broadening density of states. The results show that quantum effect is greatly dependent on the magnitude of applied strain, gate voltage, channel length, and oxide thickness. The discrepancies between the classical calculation and quantum calculation were also measured and it has been found to be as high as 19% drive current loss due to the quantum confinement. Our finding which is in good agreement with the published data provides significant insight into the device performance of uniaxial strained AGNRs in nanoelectronic applications.

Electronic Structure and Transport Properties of Armchair Graphene Nanoribbons

2008 ◽  
Vol 24 (02) ◽  
pp. 328-332 ◽  
Author(s):  
OUYANG Fang-Ping ◽  
◽  
◽  
XU Hui ◽  
LI Ming-Jun ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Transport Properties ◽  
Graphene Nanoribbons ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

Exciton effects in strained armchair graphene nanoribbons

2016 ◽  
Vol 30 (06) ◽  
pp. 1650021 ◽  
Author(s):  
Yonglei Jia ◽  
Junlin Liu
Keyword(s):  
Binding Energy ◽  
Excitation Energy ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Uniaxial Strain ◽  
Exciton Binding Energy ◽  
Coulomb Interactions ◽  
Optomechanical Systems ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

The exciton effects in 1-nm-wide armchair graphene nanoribbons (AGNRs) under the uniaxial strain were studied within the nonorthogonal tight-binding (TB) model, supplemented by the long-range Coulomb interactions. The obtained results show that both the excitation energy and exciton binding energy are modulated by the uniaxial strain. The variation of these energies depends on the ribbon family. In addition, the results show that the variation of the exciton binding energy is much weaker than the variation of excitation energy. Our results provide new guidance for the design of optomechanical systems based on graphene nanoribbons.

Electronic properties of armchair graphene nanoribbons under uniaxial strain and electric field

2018 ◽  
Vol 32 (24) ◽  
pp. 1850263 ◽  
Author(s):  
Li-Feng Jiang ◽  
Lei Xu ◽  
Jun Zhang
Keyword(s):  
Electric Field ◽  
Electronic Properties ◽  
Energy Gap ◽  
Graphene Nanoribbons ◽  
Uniaxial Strain ◽  
Quantum Phenomenon ◽  
Suitable Combination ◽  
Armchair Graphene Nanoribbons ◽  
Opening And Closing ◽  
Armchair Graphene

The armchair graphene nanoribbons (AGNRs) can be either semiconducting or metallic, depending on their widths. We investigate the electronic properties of AGNRs under uniaxial strain and electric field. We find that the bulk gap decreases gradually with the increase of the electric field for semiconducting case, but it cannot vanish completely in an appropriate range, which is similar to that of a single uniaxial strain. However, a suitable combination of electric field and uniaxial strain can lead to that the energy gap completely vanishes and reopens. For the metallic case, the bulk gap can display the same opening and closing behavior under an electric field and uniaxial strain. Finally, an interesting quantum phenomenon is obtained by applying a perpendicular magnetic field.

Negative differential resistance induced by SiNx co-dopant in armchair graphene nanoribbon

2014 ◽  
Vol 28 (29) ◽  
pp. 1450229 ◽  
Author(s):  
Cai-ping Cheng ◽  
Hui-fang Hu ◽  
Zhao-jin Zhang ◽  
Quanhui Liu ◽  
Ying Chen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Negative Differential Resistance ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Differential Resistance ◽  
Functional Theory ◽  
Co Doping ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene Nanoribbon ◽  
Armchair Graphene

By adopting density functional theory in combination with nonequilibrium Green's functions, we investigated the electronic structure and transport properties of silicon/nitrogen ( Si / N ) co-doping armchair graphene nanoribbons (AGNRs) with SiN x co-dopant incorporated in neighboring carbon atoms. The results demonstrate that the electronic structure can be modulated by introducing SiN x co-dopants in AGNRs. The striking negative differential resistance behaviors in the range of low bias can be observed in Si / N co-doped AGNR devices. These remarkable properties suggest the potential application of Si / N co-doping AGNRs in molectronics.

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