scholarly journals Band structure and gaps of triangular graphene superlattices

2010 ◽  
Vol 368 (1932) ◽  
pp. 5391-5402 ◽  
Author(s):  
F. Guinea ◽  
Tony Low
Keyword(s):  
Band Structure ◽  
Brillouin Zone ◽  
High Symmetry ◽  
Long Wavelength ◽  
General Properties ◽  
Magnetic Superlattices

The general properties of long wavelength triangular graphene superlattices are studied. It is shown that Dirac points with and without gaps can arise at a number of high-symmetry points of the Brillouin zone. The existence of gaps can lead to insulating behaviour at commensurate fillings. Strain and magnetic superlattices are also discussed.

Effects of Asymmetrical Rotated Rectangular Basis in Two-Dimensional Gyromagnetic Photonic Crystals

2013 ◽  
Vol 834-836 ◽  
pp. 885-888
Author(s):  
Hui Ling Sun ◽  
Qing Bo Li ◽  
Hua Bao Chen ◽  
Bao Ding Chen
Keyword(s):  
Photonic Crystals ◽  
Band Structure ◽  
Band Gap ◽  
Brillouin Zone ◽  
Square Lattice ◽  
High Symmetry ◽  
Two Dimensional ◽  
Symmetry Line

The twist effects of the bands during the rotation of rectangular bases are analysed in two-dimensional gyromagnetic photonic crystals with a square lattice. We find that extrema’s position have been dislocated from the high-symmetry line in the whole area of the first Brillouin zone (BZ), resulting in erroneous values for the band gap. These make us to calculate the whole first BZ to obtain the authentic band structure instead of boundary calculation.

Dielectric band structure of crystals: General properties and calculations for silicon

1981 ◽  
Vol 24 (2) ◽  
pp. 985-999 ◽  
Author(s):  
R. Car ◽  
E. Tosatti ◽  
S. Baroni ◽  
S. Leelaprute
Keyword(s):  
Band Structure ◽  
General Properties

Bulk and Surface Electronic Structure of GaN Measured Using Angle-Resolved Photoemission, Soft X-ray Emission and Soft X-ray Absorption

1996 ◽  
Vol 449 ◽  
Author(s):  
Kevin E. Smith ◽  
Sarnjeet S Dhesi ◽  
Laurent-C. Duda ◽  
Cristian B Stagarescu ◽  
J. H. Guo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Absorption Spectra ◽  
Conduction Band ◽  
Brillouin Zone ◽  
Emission Spectra ◽  
Partial Density ◽  
High Symmetry ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTThe electronic structure of thin film wurtzite GaN has been studied using a combination of angle resolved photoemission, soft x-ray absorption and soft x-ray emission spectroscopies. We have measured the bulk valence and conduction band partial density of states by recording Ga L- and N K- x-ray emission and absorption spectra. We compare the x-ray spectra to a recent ab initio calculation and find good overall agreement. The x-ray emission spectra reveal that the top of the valence band is dominated by N 2p states, while the x-ray absorption spectra show the bottom of the conduction band as a mixture of Ga 4s and N 2p states, again in good agreement with theory. However, due to strong dipole selection rules we can also identify weak hybridization between Ga 4s- and N 2p-states in the valence band. Furthermore, a component to the N K-emission appears at approximately 19.5 eV below the valence band maximum and can be identified as due to hybridization between N 2p and Ga 3d states. We report preliminary results of a study of the full dispersion of the bulk valence band states along high symmetry directions of the bulk Brillouin zone as measured using angle resolved photoemission. Finally, we tentatively identify a non-dispersive state at the top of the valence band in parts of the Brillouin zone as a surface state.

Photonic Band Structure of Nanochannel Glass Materials

1996 ◽  
Vol 431 ◽  
Author(s):  
A. Rosenberg ◽  
R. J. Tonucci ◽  
H.-B. Lin
Keyword(s):  
Band Structure ◽  
Brillouin Zone ◽  
Near Infrared ◽  
Nearest Neighbor ◽  
Dielectric Structure ◽  
Zone Boundary ◽  
Photonic Band Structure ◽  
Brillouin Zone Boundary ◽  
Photonic Band ◽  
Good Agreement

AbstractWe demonstrate that nanochannel glass (NCG) materials are ideal for investigating twodimensional (2D) photonic band-structure effects. The NCG materials we have studied consist of triangular arrays of glass cylinders embedded in a glass matrix, having center-tocenter nearest-neighbor separations from 0.54 to 1.08 μm. The indices of refraction of the two glasses differ by less than 0.02 in the relevant spectral region. Narrow attenuation features occur whenever the dispersion relation for light propagating within such a periodic dielectric structure crosses a Brillouin zone boundary. The attenuations corresponding to the first Brillouin zone appear in the near-infrared (IR), at wavelengths between 1 and 3 μm, in good agreement with calculations.

Impact of band structure of Ohmic contact layers on the response feature of p-i-n very long wavelength type II InAs/GaSb superlattice photodetector

2015 ◽  
Vol 106 (26) ◽  
pp. 263502 ◽  
Author(s):  
Jianliang Huang ◽  
Wenquan Ma ◽  
Yanhua Zhang ◽  
Yulian Cao ◽  
Ke Liu ◽  
...  
Keyword(s):  
Band Structure ◽  
Ohmic Contact ◽  
Type Ii ◽  
Long Wavelength ◽  
Response Feature

scholarly journals Assessment of Functionals for First-Principle Studies of the Structural and Electronic Properties ofδ-Bi2O3

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
D. H. Galván ◽  
R. Núñez-González ◽  
R. Rangel ◽  
P. Alemany ◽  
A. Posada-Amarillas
Keyword(s):  
Band Structure ◽  
Charge Density ◽  
Electronic Properties ◽  
Density Of States ◽  
Lattice Parameter ◽  
Experimental Result ◽  
Ionic Character ◽  
High Symmetry ◽  
Density Profiles ◽  
Structural And Electronic Properties

Fully relativistic full-potential density functional calculations with an all-electron linearized augmented plane waves plus local orbitals method were carried out to perform a comparative study on the structural and electronic properties of the cubic oxideδ-Bi2O3phase, which is considered as one of the most promising materials in a variety of applications including fuel cells, sensors, and catalysts. Three different density functionals were used in our calculations, LDA, the GGA scheme in the parametrization of Perdew, Burke, and Ernzerhof (PBE96), and the hybrid scheme of Perdew-Wang B3PW91. The examined properties include lattice parameter, band structure and density of states, and charge density profiles. For this modification the three functionals reveal the characteristics of a metal and the existence of minigaps at high symmetry points of the band structure when spin-orbit coupling is taken into account. Density of states exhibits hybridization of Bi 6s and O 2p orbitals and the calculated charge density profiles exhibit the ionic character in the chemical bonding of this compound. The B3PW91 hybrid functional provided a better agreement with the experimental result for the lattice parameter, revealing the importance of Hartree-Fock exchange in this compound.

First Principles Calculations of Graphene Doped with Al, P and Si Heteroatoms

2017 ◽  
Vol 16 ◽  
pp. 52-55 ◽  
Author(s):  
Maria Teresa Romero ◽  
Yuliana Avila Alvarado ◽  
Reyes Garcia-Diaz ◽  
Carlos Rodriguez Garcia ◽  
Raul Ochoa Valiente ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Density Functional ◽  
Pristine Graphene ◽  
High Symmetry ◽  
Linear Dispersion ◽  
Graphene Layers ◽  
Doping Effects ◽  
Semiconductor Behavior ◽  
Quantum Espresso

In this work, studies of the doping effects on the electronic and structural properties of graphene were performed. Calculations have been done within the periodic density functional theory (DFT) as implemented in PWscf code of the Quantum Espresso Package. Graphene layers have been modeled using the 4x4 periodic supercells. The doping is explored considering phosphorus (P), aluminum (Al) and silicon (Si) heteroatoms. One heteroatom per supercell was considered. Electronic structure results show that the pristine graphene has a linear dispersion at high symmetry K point and zero gap. Band structure of graphene doped with Al atoms exhibit a metal behavior since a valence band crosses the Fermi level. Graphene doped with P also presents a metal behavior but in this case a conduction band crosses the Fermi level. In addition, when the dopant is Si the band structure shows a semiconductor behavior with a 0.3 eV gap. In all cases, the zero gap energy characteristic of graphene was changed by dopant heteroatom. The Dirac lineal dispersion relation is preserved only in the pristine graphene.

scholarly journals Solution of Secular Determinants for Group IV And III?V Semiconductors by Symmetry Analysis

1973 ◽  
Vol 26 (4) ◽  
pp. 501 ◽  
Author(s):  
SJ Joshua ◽  
D Morgan
Keyword(s):  
Band Structure ◽  
Numerical Solution ◽  
Energy Band ◽  
Form Factors ◽  
Group Iv ◽  
Energy Band Structure ◽  
High Symmetry ◽  
Orthogonal Matrices ◽  
Symmetry Properties ◽  
Secular Determinant

A brief discussion is given of the symmetry properties of the energy band structure and the method of constructing orthogonal matrices at high symmetry points for group IV and III-V semiconductors. By means of examples it is shown how to factorize the n x n secular determinant formed by using the pseudopotential form factors of Cohen and Bergstresser (1966), thereby permitting easy numerical solution.

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