scholarly journals On the Energy Gaps Induced by a Semiconducting Substrate in the Graphene Density of States

2015 ◽  
Vol 9 (12) ◽  
pp. 234
Author(s):  
Sergey Yurevich Davydov ◽  
Alexander Alexandrovich Lebedev
Keyword(s):  
Electronic Spectrum ◽  
Density Of States ◽  
Energy Gap ◽  
Epitaxial Graphene ◽  
Energy Gaps ◽  
Densities Of States ◽  
Analytical Expressions ◽  
Semiconducting Substrate ◽  
Numerical Estimations

<p class="zhengwen"><span lang="EN-GB">The analytical expressions for the densities of states for graphene formed on semiconducting substrates are obtained. The problem on the induced gap is studied thoroughly. It is shown, that graphene electronic spectrum according to the relation between the system’s parameters can contain two gaps or one gap, overlapping with the energy gap of substrate. The gaps width dependences on the coupling regimes (tight and weak) are obtained. Numerical estimations are fulfilled for the epitaxial graphene on 6H-SiC{0001}.</span></p>

Energy Gaps Induced by a Semiconducting Substrate in the Epitaxial Graphene Density of States

2013 ◽  
Vol 740-742 ◽  
pp. 141-144
Author(s):  
Sergey Yu. Davydov ◽  
Alexander A. Lebedev ◽  
Sergey P. Lebedev
Keyword(s):  
Simple Model ◽  
Density Of States ◽  
Energy Gap ◽  
Epitaxial Graphene ◽  
Layer Graphene ◽  
Energy Gaps ◽  
The One ◽  
Semiconducting Substrate

The simple model for the one-layer graphene energy gaps induced by the substrate energy gap is pro-posed.

scholarly journals Простые модели латеральных гетероструктур

2018 ◽  
Vol 60 (7) ◽  
pp. 1389
Author(s):  
С.Ю. Давыдов
Keyword(s):  
Charge Transfer ◽  
Density Of States ◽  
Function Method ◽  
Tight Binding ◽  
Tight Binding Approximation ◽  
Densities Of States ◽  
Infinite Lattices ◽  
Band Spectra ◽  
Analytical Expressions ◽  
Lateral Heterostructure

AbstractGeneral analytical expressions for densities of states of a lateral heterostructure, formed by the contact of two square semi-infinite lattices with single-band and two-band spectra, were obtained in the tight-binding approximation by the Green’s function method. The semi-elliptical density of states was used for numerical estimates, and the model of two interacting dimers was proposed to estimate the charge transfer. Application of this approach to description of lateral epitaxial and graphene-like heterostructures is discussed.

scholarly journals Углеродные наноструктуры на полупроводниковой подложке

2019 ◽  
Vol 61 (6) ◽  
pp. 1214
Author(s):  
С.Ю. Давыдов
Keyword(s):  
Boron Nitride ◽  
Carbon Nanostructures ◽  
Graphene Nanoribbons ◽  
Strong Coupling Regime ◽  
Main Attention ◽  
Occupation Numbers ◽  
Analytical Expressions ◽  
Semiconducting Substrate ◽  
Lateral Heterostructure ◽  
Numerical Estimations

AbstractThe analytical expressions for the density of states and the occupation numbers are obtained for simple models of carbon nanostructures (graphene–boron nitride lateral heterostructure, decorated zigzag edges of semi-infinity graphene and graphene nanoribbons, and decorated carbyne). The main attention is placed to the strong-coupling regime of the nanostructures with a semiconducting substrate. The numerical estimations are given for the SiC substrate.

scholarly journals Цепочечная модель зигзагообразного контакта латеральных графеноподобных гетероструктур

2018 ◽  
Vol 44 (21) ◽  
pp. 55
Author(s):  
С.Ю. Давыдов
Keyword(s):  
Boron Nitride ◽  
Density Of States ◽  
Structural Model ◽  
Hexagonal Boron Nitride ◽  
Two Dimensional ◽  
Occupation Numbers ◽  
Densities Of States ◽  
Spectrum Density ◽  
Analytical Expressions ◽  
Good Agreement

AbstractA simple structural model is proposed for the zigzag interface formed by contacting two-dimensional graphene-like compounds AB and CD (both free and formed on a metal). For the graphene–hexagonal boron nitride system, analytical expressions for the electron spectrum, density of states, and atom occupation numbers at the interface are obtained. The results of calculating the densities of states and occupation numbers within two alternative approximations are in good agreement.

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.

GAP-LABELING PROPERTIES OF THE ENERGY SPECTRUM FOR TWO-DIMENSIONAL FIBONACCI QUASILATTICES

1995 ◽  
Vol 09 (01) ◽  
pp. 55-66
Author(s):  
YOUYAN LIU ◽  
WICHIT SRITRAKOOL ◽  
XIUJUN FU
Keyword(s):  
Energy Spectrum ◽  
Density Of States ◽  
Energy Gap ◽  
Fractional Part ◽  
Numerical Results ◽  
Step Height ◽  
Integrated Density Of States ◽  
Two Dimensional

We have analytically obtained the occupation probabilities on subbands of the hierarchical energy spectrum and the step heights of the integrated density of states for two-dimensional Fibonacci quasilattices. Based on the above results, the gap-labeling properties of the energy spectrum are found, which claim that the step height is equal to {mτ}, where the braces denote the fractional part, and m is an integer that can be used to label the corresponding energy gap. Numerical results confirm these results very well.

Determination of Density of Localized States in Amorphous Silicon Alloys From the Low Field Conductance of Thin N-I-N Diodes

1985 ◽  
Vol 49 ◽  
Author(s):  
Michael Shur ◽  
Michael Hack
Keyword(s):  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Bulk Density ◽  
Density Of States ◽  
Energy Gap ◽  
Localized States ◽  
New Technique ◽  
Silicon Alloys ◽  
Low Field ◽  
Density Of Localized States

AbstractWe describe a new technique to determine the bulk density of localized states in the energy gap of amorphous silicon alloys from the temperature dependence of the low field conductance of n-i-n diodes. This new technique allows us to determine the bulk density of states in the centre of a device, and is very straightforward, involving fewer assumptions than other established techniques. Varying the intrinsic layer thickness allows us to measure the,density of states within approximately 400 meV of midgap.We measured the temperature dependence of the low field conductance of an amorphous silicon alloy n-i-n diode with an intrinsic layer thjckness of 0.45 microns and deduced the density of localised states to be 3xlO16cm−3 eV−1 at approximately 0.5 eV below the bottom of the conduction band. We have also considered the high bias region (the space charge limited current regime) and proposed an interpolation formula which describes the current-voltage characteristics of these structures at all biases and agrees well with our computer simulation based on the solution of the complete system of transport equations.

Tc of intermediate coupling superconductors with a variable electronic density of states (EDOS)

1983 ◽  
Vol 61 (2) ◽  
pp. 212-219
Author(s):  
M. Ashraf ◽  
J. P. Carbotte
Keyword(s):  
Density Of States ◽  
Chemical Potential ◽  
Present Calculation ◽  
Zero Temperature ◽  
Intermediate Coupling ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Dimensionless Ratio ◽  
Arbitrary Position ◽  
Analytical Expressions

Using the model of Leavens and Carbotte for intermediate coupling superconductors, we have derived and evaluated analytical expressions for the critical temperature Tc, and the zero temperature gap Δ0 of those superconductors with a variable electronic density of states (EDOS). EDOS is given by a Lorentzian peak superimposed on a constant background with the chemical potential falling at some arbitrary position within the peak. The most significant modifications occur for a narrow Lorentzian with the peak close to the Fermi level. The value of the dimensionless ratio 2Δ0/kBTc remains close to the Bardeen–Cooper–Schrieffer (BCS) value of 3.53. Also, the present calculation compares very favourably with a previous exact calculation.

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