Effects of band hybridization on electronic properties in tuning armchair graphene nanoribbons

2016 ◽  
Vol 94 (2) ◽  
pp. 218-225 ◽  
Author(s):  
M. Khatun ◽  
Z. Kan ◽  
A. Cancio ◽  
C. Nelson
Keyword(s):  
Fermi Level ◽  
Density Of States ◽  
Graphene Nanoribbons ◽  
Local Density ◽  
Tight Binding ◽  
Edge States ◽  
Local Density Of States ◽  
Periodic Patterns ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

We explore a model of armchair graphene nanoribbons tuned by functionalizing the edge states. Edge modifications are modeled by changing the electronic energy of the edge states in specific periodic patterns. The model can be considered to mimic a controlled doping process with different elements. The band structure, density of states, conductance, and local density of states are calculated, using the tight binding approach, Green’s function methodology, and the Landauer formula. The results show interesting behaviors, which are considerably different from the properties of the perfect nanoribbons. The hybridization of conducting bands with non-conducting bands, which appear perfectly flat in the perfect ribbon, opens up and modifies gaps in conductance near the Fermi level. One particular pattern of edge functionalization causes a strong, symmetric, and systematic band gap change about the Fermi level, modifying the electronic characteristics in the energy dispersion, density of states, local density of states, and conductance.

scholarly journals ELECTRONIC STATES AND LOCAL DENSITY OF STATES NEAR GRAPHENE CORNER EDGE

2012 ◽  
Vol 11 ◽  
pp. 151-156 ◽  
Author(s):  
YUJI SHIMOMURA ◽  
YOSITAKE TAKANE ◽  
KATSUNORI WAKABAYASHI
Keyword(s):  
Density Of States ◽  
Nearest Neighbor ◽  
Local Density ◽  
Tight Binding ◽  
Localized States ◽  
Destructive Interference ◽  
Edge States ◽  
Local Density Of States ◽  
Binding Model ◽  
Recursion Method

We study that stability of edge localized states in semi-infinite graphene with a corner edge of the angles 60°, 90°, 120° and 150°. We adopt a nearest-neighbor tight-binding model to calculate the local density of states (LDOS) near each corner edge using Haydock's recursion method. The results of the LDOS indicate that the edge localized states stably exist near the 60°, 90°, and 150° corner, but locally disappear near the 120° corner. By constructing wave functions for a graphene ribbon with three 120° corners, we show that the local disappearance of the LDOS is caused by destructive interference of edge states and evanescent waves.

Electronic Properties of Au-Doped Narrow Armchair Graphene Nanoribbons: A First Principle Calculations

2014 ◽  
Vol 1015 ◽  
pp. 155-158
Author(s):  
Wei Hua Wang ◽  
Cui Lan Zhao ◽  
Xin Jun Ma
Keyword(s):  
Charge Density ◽  
Valence Band ◽  
Density Of States ◽  
Energy Gap ◽  
Graphene Nanoribbons ◽  
Local Density ◽  
Electronic States ◽  
Electronic Energy ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

The centre Au-doped armchair graphene nanoribbons (AGNRs) are investigated using the local density approximation based on density function theory. The charge density, electronic energy band and project density of states of centre Au-doped AGNRs are calculated. Our results indicate the charge density is transferred between C and Au atoms and mainly located on the Au atoms. The centre Au-doped AGNRs are an indirect band gap semiconductor with an energy gap of 1.046 eV. The Fermi level is located on valence band so that the AGNRs of doping Au become into degenerate semiconductor. The project density of states is calculated to reveal localization and hybridization between C-2pand Au-6s, 5delectronic states. The localization and hybridization are much stronger in the valence band. The hybridization between C-2pand Au-6pelectronic states are strongly in the conduction band.

scholarly journals Role Played by Edge-Defects in the Optical Properties of Armchair Graphene Nanoribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3229
Author(s):  
Thi-Nga Do ◽  
Godfrey Gumbs ◽  
Danhong Huang ◽  
Bui D. Hoi ◽  
Po-Hsin Shih
Keyword(s):  
Optical Properties ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Edge States ◽  
Binding Model ◽  
Edge Defect ◽  
Flat Bands ◽  
Edge Defects ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

We explore the implementation of specific optical properties of armchair graphene nanoribbons (AGNRs) through edge-defect manipulation. This technique employs the tight-binding model in conjunction with the calculated absorption spectral function. Modification of the edge states gives rise to the diverse electronic structures with striking changes in the band gap and special flat bands at low energy. The optical-absorption spectra exhibit unique excitation peaks, and they strongly depend on the type and period of the edge extension. Remarkably, there exist the unusual transition channels associated with the flat bands for selected edge-modified systems. We discovered the special rule governing how the edge-defect influences the electronic and optical properties in AGNRs. Our theoretical prediction demonstrates an efficient way to manipulate the optical properties of AGNRs. This might be of importance in the search for suitable materials designed to have possible technology applications in nano-optical, plasmonic and optoelectronic devices.

scholarly journals Role Played by Edge-Defects in the Optical Properties of Armchair Graphene Nanoribbons

2021 ◽  
Author(s):  
Thi-Nga Do ◽  
Godfrey Gumbs ◽  
Danhong Huang ◽  
D. Hoi Bui ◽  
Po-Hsin Shih
Keyword(s):  
Optical Properties ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Edge States ◽  
Binding Model ◽  
Edge Defect ◽  
Flat Bands ◽  
Edge Defects ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

We explore the implementation of specific optical properties of armchair graphene nanoribbons (AGNRs) through edge-defect manipulation. This technique employs the tight-binding model in conjunction with the calculated absorption spectral function. Modification of the edge states gives rise to the diverse electronic structures with striking changes in the band gap and special flat bands at low energy. The optical-absorption spectra exhibit exotic excitation peaks and they strongly depend on the type and period of the edge extension. Remarkably, there exist the unusual transition channels associated with the flat bands for selected edge-modified systems. We discover the special rule governing how the edge-defect influences the electronic and optical properties in AGNRs. Our theoretical prediction demonstrates an efficient way to manipulate the optical properties of AGNRs. This might be of importance in the search for suitable materials designed to have possible technology applications in nano-optical, plasmonic and optoelectronic devices.

Family-dependent magnetism in atomic boron adsorbed armchair graphene nanoribbons

2019 ◽  
Vol 7 (21) ◽  
pp. 6241-6245 ◽  
Author(s):  
Wei-Wei Yan ◽  
Xiao-Fei Li ◽  
Xiang-Hua Zhang ◽  
Xinrui Cao ◽  
Mingsen Deng
Keyword(s):  
Fermi Level ◽  
Graphene Nanoribbons ◽  
Spin Splitting ◽  
Localized State ◽  
The Family ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene ◽  
Boron Adsorption

Boron adsorption induces a heavily localized state right at the Fermi level only in the family of W = 3p + 1 and thus spin-splitting occurs spontaneously.

ENERGY GAP DEPENDENCE ON ANION CONCENTRATION FOR GaxIn1-xAsyP1-y QUATERNARY ALLOY BY RECURSION METHOD

2004 ◽  
Vol 18 (18) ◽  
pp. 955-962
Author(s):  
MUSA EL-HASAN ◽  
REZEK ESTATIEH
Keyword(s):  
Density Of States ◽  
Energy Gap ◽  
Local Density ◽  
Tight Binding ◽  
Quaternary Alloy ◽  
Average Density ◽  
Local Density Of States ◽  
Recursion Method ◽  
Orbital Decomposition ◽  
Lattice Matched

Three terminators have been tested, square root terminator, quadreture terminator and linear terminator, it was found that the linear terminator is the best, so it was used in calculating local density of states (LDOS) and it's orbital decomposition, alloy average density of states, and energy gap for different anion concentrations for InP lattice matched alloy. The results were compared with our previous calculations of (LDOS), and results from other methods. Energy gap was compared with experimental measurements. A five orbital sp3s* per atom model was used in the tight-binding representation of the Hamiltonian.

Electronic band structure of silver low-index surfaces: a tight-binding study

2020 ◽  
Vol 98 (5) ◽  
pp. 488-496
Author(s):  
H.J. Herrera-Suárez ◽  
A. Rubio-Ponce ◽  
D. Olguín
Keyword(s):  
Band Structure ◽  
Density Of States ◽  
Electronic Band Structure ◽  
Local Density ◽  
Tight Binding ◽  
Theoretical Data ◽  
Binding Study ◽  
Local Density Of States ◽  
Electronic Band ◽  
Tight Binding Method

We studied the electronic band structure and corresponding local density of states of low-index fcc Ag surfaces (100), (110), and (111) by using the empirical tight-binding method in the framework of the Surface Green’s Function Matching formalism. The energy values for different surface and resonance states are reported and a comparison with the available experimental and theoretical data is also done.

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.

scholarly journals Strain and screening effects on field emission properties of armchair graphene nanoribbon arrays: a first-principles study

RSC Advances ◽  
2018 ◽  
Vol 8 (40) ◽  
pp. 22625-22634 ◽  
Author(s):  
Han Hu ◽  
Siow Mean Loh ◽  
Tsan-Chuen Leung ◽  
Ming-Chieh Lin
Keyword(s):  
Field Emission ◽  
First Principles ◽  
Graphene Nanoribbons ◽  
Local Density ◽  
First Principles Calculations ◽  
Emission Properties ◽  
Field Emission Properties ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene Nanoribbon ◽  
Armchair Graphene

The field screening effect on the field-emission properties of armchair graphene nanoribbons (AGNRs) under strain has been studied using first-principles calculations with local density approximation (LDA).

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