scholarly journals Electronic and optical properties of ternary alloys ZnxCd1−xS, ZnxCd1−xSe, ZnSxSe1−x, MgxZn1−xSe

2017 ◽  
Vol 35 (1) ◽  
pp. 32-39
Author(s):  
K. Benchikh ◽  
H. Abid ◽  
M. Benchehima
Keyword(s):  
Optical Properties ◽  
Detailed Comparison ◽  
Ternary Alloys ◽  
Band Structures ◽  
Virtual Crystal Approximation ◽  
Electronic And Optical Properties ◽  
Empirical Pseudopotential Method ◽  
Direct Band ◽  
Alloy Concentration ◽  
Good Agreement

AbstractThe empirical pseudopotential method (EPM) within the virtual crystal approximation (VCA) is used to calculate the electronic and optical properties of ternary alloys ZnxCd1−xS, ZnxCd1−xSe, ZnSxSe1−x and MgxZn1−xSe. The alloy band structures and energy gaps are calculated using VCA which incorporates the compositional disorder as an effective potential. The calculated band structures for the ZnxCd1−xS, ZnxCd1−xSe and ZnSxSe1−x alloys show a direct band gap in the whole range of the concentration except for the MgxZn1−xSe alloy which presents a crossover from the direct gap to the indirect one.Also the dependence of the refractive index on the concentration is calculated for each ternary alloy. This parameter is found to depend nonlinearly on the alloy concentration. A detailed comparison of our results with experimental data and works of other authors has led to a good agreement.

Calculation of Electronic and Optical Properties of Zinc-Blende MGX ZN1-X S

2011 ◽  
Vol 324 ◽  
pp. 249-252 ◽  
Author(s):  
Nadjla Mostefai ◽  
Nadir Bouarissa ◽  
Abdelhak Belkhir
Keyword(s):  
Optical Properties ◽  
Composition Dependence ◽  
Ternary Alloys ◽  
Virtual Crystal Approximation ◽  
Electronic And Optical Properties ◽  
Zinc Blende ◽  
Blue Wavelength ◽  
Indirect Band Gap ◽  
Zinc Blende Structure ◽  
Good Agreement

The electronic and optical properties of the MgxZn1-xS semiconductor ternary alloys crystallizing in the Zinc Blende structure are calculated using the empirical pseudopotential method (EPM) coupled with the virtual crystal approximation (VCA). The composition dependence of the direct and indirect band gap energies as well as the antisymmetric gap are investigated in the composition range 0 up to 1. Other quantities such as refractive index and coefficient of reflection are also obtained by means of different existing models. Our results are generally in good agreement with those available in the literature. The obtained informations could be useful for the feature design of blue wavelength optoelectronic devices.

scholarly journals First-Principles Calculations of the Structural, Electronic and Optical Properties of Yttrium-Doped SnO2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nabil Beloufa ◽  
Youcef Chechab ◽  
Souad Louhibi-Fasla ◽  
Abbes Chahed ◽  
Samir Bekheira ◽  
...  
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Level Shifts ◽  
Type Semiconductor ◽  
Direct Band ◽  
P Type ◽  
Theoretical Results ◽  
Good Agreement

Abstract We use FP-LAPW method to study structural, electronic, and optical properties of the pure and Y-doped SnO2. The results show that by Y doping of SnO2 the band gaps are broadened, and still direct at Γ-point. For pure SnO2 material, the obtained values of the direct band gap are 0.607 eV for GGA-PBE and 2.524 eV for GGATB-mBJ, respectively. This later is in good agreement with the experimental data and other theoretical results. The Fermi level shifts into the valence band and exhibits p-type semiconductor character owing mainly from the orbital 4d-Y. Additionally, the calculated optical properties reveal that all concentrations are characterized by low reflectivity and absorption via wavelength λ (nm) in the visible light and near-infrared (NIR) ranges, which leads to a redshift in the optical transparency.

STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF THE TETRAGONAL PHASE OFCaSiO3PEROVSKITE UNDER PRESSURE: FIRST-PRINCIPLES CALCULATIONS

2011 ◽  
Vol 25 (01) ◽  
pp. 41-52 ◽  
Author(s):  
ZI-JIANG LIU ◽  
CAI-RONG ZHANG ◽  
XIAO-WEI SUN ◽  
LU WANG ◽  
TING SONG ◽  
...  
Keyword(s):  
Optical Properties ◽  
Pressure Dependence ◽  
First Principles ◽  
Local Density ◽  
Electronic And Optical Properties ◽  
Plane Wave Method ◽  
Direct Band ◽  
Electron Energy Loss ◽  
Calculated Equilibrium ◽  
Good Agreement

First principles studies of structural, elastic, electronic and optical properties of tetragonal CaSiO3perovskite under pressure are reported using the pseudopotential plane wave method within the local density approximation (LDA). The calculated equilibrium lattice is in good agreement with the available experimental data. The elastic constants and their pressure dependence are calculated using the static finite strain technique. A linear pressure dependence of the elastic stiffnesses is found. Band structures show that tetragonal CaSiO3perovskite is a direct band gap material. In order to understand the optical properties of tetragonal CaSiO3perovskite, the dielectric function, absorption coefficient, optical reflectivity, refractive index, extinction coefficient, and electron energy loss are calculated for radiation up to 40 eV. This is the first quantitative theoretical prediction of the elastic, electronic and optical properties of tetragonal CaSiO3perovskite, and it still awaits experimental confirmation.

AB INITIO STUDY OF STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF MgxCd1-xX (X = S, Se, Te) ALLOYS

2012 ◽  
Vol 26 (30) ◽  
pp. 1250168 ◽  
Author(s):  
N. A. NOOR ◽  
A. SHAUKAT
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Ternary Alloys ◽  
Full Potential ◽  
Generalized Gradient ◽  
Calculated Density ◽  
Electronic And Optical Properties ◽  
Direct Band

This study describes structural, electronic and optical properties of Mg x Cd 1-x X (X = S, Se, Te) alloys in the complete range 0≤x ≤1 of composition x in the zinc-blende (ZB) phase with the help of full-potential linearized augmented plane wave plus local orbitals (FP-LAPW+lo) method within density functional theory (DFT). In order to calculate total energy, generalized gradient approximation (Wu–Cohen GGA) has been applied, which is based on optimization energy. For electronic structure calculations, the corresponding potential is being optimized by Engel–Vosko GGA formalism. Our calculations reveal the nonlinear variation of lattice constant and bulk modulus with different concentration for the end binary and their ternary alloys, which slightly deviates from Vegard's law. The calculated band structures show a direct band gap for all three alloys with increasing order in the complete range of the compositional parameter x. In addition, we have discussed the disorder parameter (gap bowing) and concluded that the total band gap bowing is substantially influenced by the chemical (electronegativity) contribution. The calculated density of states (DOS) of these alloys is discussed in terms of contribution from various s-, p- and d-states of the constituent atoms and charge density distributions plots are analyzed. Optical properties have been presented in the form of the complex dielectric function ε(ω), refractive index n(ω) and extinction coefficient k(ω) as function of the incident photon energy, and the results have been compared with existing experimental data and other theoretical calculations.

scholarly journals Structural, elastic, electronic and optical properties of the half-Heusler ScPtSb and YPtSb compounds under pressure

2021 ◽  
Vol 24 (4) ◽  
pp. 43702
Author(s):  
M. Radjai ◽  
A. Bouhemadou ◽  
D. Maouche
Keyword(s):  
Optical Properties ◽  
Mechanical Stability ◽  
Spin Orbit Coupling ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Direct Band ◽  
Electronic Band Structures ◽  
Calculated Equilibrium ◽  
Good Agreement

First-principles calculations using the plane-wave pseudopotential method within the generalized gradient approximation method were performed to study the pressure dependence of the structural, elastic, electronic and optical properties for the half-Heusler compounds ScPtSb and YPtSb in a cubic MgAgAs-type structure. The calculations were performed with the inclusion of spin-orbit coupling. The calculated equilibrium lattice parameters are in good agreement with the available experimental and theoretical values. The crystal rigidity and mechanical stability were discussed using the elastic constants and related parameters, namely bulk modulus, shear modulus, Debye temperature, Poisson's coefficient, Young's modulus and isotropic sound velocities. The calculated electronic band structures show that ScPtSb has an indirect gap of Γ-X type, whereas YPtSb has a direct band gap of Γ-Γ type. Furthermore, the effect of pressure on the optical properties, namely the dielectric function, absorption spectrum, refractive index, extinction coefficient, reflectivity and energy-loss spectrum is investigated for both compounds ScPtSb and YPtSb.

scholarly journals First principles study of structure, electronic and optical properties of Y3Fe5O12 in cubic and trigonal phases

2015 ◽  
Vol 33 (1) ◽  
pp. 169-174 ◽  
Author(s):  
Shen Tao ◽  
Hu Chao ◽  
Dai Hailong ◽  
Yang Wenlong ◽  
Liu Hongchen ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Energy Loss ◽  
First Principles ◽  
Structural Parameters ◽  
Band Gaps ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Direct Band ◽  
Experimental Values

AbstractFirst principles calculations have been performed to investigate the structure, electronic and optical properties of Y3Fe5O12. Both the cubic and trigonal phases have been considered in our calculation. The calculated structural parameters are slightly larger than the experimental values. The band structures show that Y3Fe5O12 in cubic and trigonal phases have direct band gaps of 0.65 and 0.17 eV. The calculations of dielectric function, absorption, extinction coefficient, refractive index, energy loss function and reflectivity are presented.

First-principles investigation of the structural, elastic, electronic, and optical properties of semiconducting AgBr1–xIx (0 ≤ x ≤ 1) ternary alloys in rock-salt and zinc blende structures

2020 ◽  
Vol 98 (9) ◽  
pp. 834-848
Author(s):  
H. Rekab-Djabri ◽  
Mohamed Drief ◽  
Manal M. Abdus Salam ◽  
Salah Daoud ◽  
F. El Haj Hassan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Rock Salt ◽  
Density Functional ◽  
Local Density ◽  
Ternary Alloys ◽  
Full Potential ◽  
Zinc Blende ◽  
Lmto Method ◽  
Direct Band

In this work, first principle calculations of the structural, electronic, elastic, and optical properties of novel AgBr1–xIx ternary alloys in rock-salt (B1) and zinc-blende (B3) structures are presented. The calculations were performed using the full-potential linear muffin-tin orbital (FP-LMTO) method within the framework of the density functional theory (DFT). The exchange and correlation potentials were treated according to the local density approximation (LDA). The lattice constants for the B1 and B3 phases versus iodide concentration (x) were found to deviate slightly from the linear relationship of Vegard’s law. The calculated electronic properties showed that AgBr1–xIx alloys in the B3 structure have a direct band gap (Γ – Γ) for all concentrations of x, which means that they can be used in long-wavelength optoelectronic applications, while in the B1 structure they have an indirect (Γ – R) band gap. The elastic constants Cij, shear modulus G, Young’s modulus E, Poisson’s ratio ν, index of ductility B/G, sound velocities vt, vl, and vm, and Debye temperature θD were also reported and analyzed. By incorporating the basic optical properties, we discussed the dielectric function, refractive index, optical reflectivity, absorption coefficient, and optical conductivity in terms of incident photon energy up to 13.5 eV. The present results were found to be in good agreement with the available experimental and other theoretical results.

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