scholarly journals First-principles calculations of elastic and optical properties of Aluminum Nitride (AlN) in cubic and hexagonal phase

2021 ◽  
Vol 49 (1) ◽  
Author(s):  
Burhan Ahmed ◽  
◽  
B. Indrajit Sharma ◽  
Keyword(s):  
Optical Properties ◽  
Energy Range ◽  
Rock Salt ◽  
Density Functional ◽  
High Energy ◽  
Wurtzite Phase ◽  
Metallic Behavior ◽  
Zinc Blende ◽  
Good Agreement ◽  
Three Phases

Investigation of elastic and optical properties of AlN in rock salt, zinc blende, and wurtzite phase is done under the framework of Density Functional Theory (DFT) with modified Becke Johnson Generalised Gradient Approximation (mBJ-GGA) as exchange-correlation functional. Elastic properties conclude the bonding nature of the AlN in the rock salt phase is covalent and stiffest, while the bonding nature in the zinc blende and wurtzite phase is found to be ionic and less stiff. The ratio of bulk modulus to shear modulus indicates AlN is brittle in all three phases. The calculated Debye temperature in all three phases is in good agreement with the available theoretical and experimental works. The optical properties calculation shows the AlN is transparent in the low energy range and it has the metallic behavior in the energy range 7.5eV to 10 eV. At the same time, the compound loses its transparency at the high energy range. Our calculated value of the refractive index of AlN in the rock salt, zinc blende, and wurtzite phases is in good agreement with the available experimental and theoretical works.

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.

Electronic and optical properties of zinc-blende GeC by first principles study

2015 ◽  
Vol 29 (20) ◽  
pp. 1550103
Author(s):  
Jinhui Zhai ◽  
Jinguang Zhai ◽  
Ajun Wan
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Dielectric Constants ◽  
Electronic And Optical Properties ◽  
Optical Functions ◽  
Zinc Blende ◽  
The Density Functional Theory ◽  
Valence Bands ◽  
Energy Dependent

The electronic and optical properties of zinc-blende (zb)[Formula: see text]GeC have been investigated using first principles calculations based on the density functional theory (DFT). The obtained band gap of zb–GeC is 2.30[Formula: see text]eV by means of Heyd–Scuseria–Ernzerhof (HSE) functional. We have discussed the energy-dependent optical functions including dielectric constants, refractive index, absorption, reflectivity, and energy-loss spectrum in detail. The results reveal that zb–GeC has a higher static dielectric constant compared with that of zb–SiC. The optical functions are mainly associated with the interband transitions from the occupied valence bands (VBs) Ge[Formula: see text][Formula: see text] and C[Formula: see text][Formula: see text] states to Ge[Formula: see text][Formula: see text], [Formula: see text] and C[Formula: see text][Formula: see text] states of the unoccupied conduction bands (CBs).

DFT study of elastic, half-metallic and optical properties of Co2V(Al, Ge, Ga and Si) compounds

2017 ◽  
Vol 31 (14) ◽  
pp. 1750109 ◽  
Author(s):  
Heidar Khosravi ◽  
Arash Boochani ◽  
Golnaz Rasolian ◽  
Shahram Solaymani ◽  
Sirvan Naderi
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Magnetic Moments ◽  
Elastic Stability ◽  
Metallic Behavior ◽  
Functional Theory ◽  
Spin Mode ◽  
Half Metallic ◽  
Lattice Constants ◽  
Optical Treatment

First-principles study of elastic, electronic and optical properties of full-Heusler Co2V(Al, Ge, Ga and Si) compounds are calculated through density functional theory (DFT) to obtain and compare the mentioned properties. Equilibrium lattice constants of these compounds are in good agreement with other works. Electronic calculations are shown full spin polarization at Fermi level for all compounds, so in the down spin, indirect bandgap is calculated as 0.33, 0.6, 0.2 and 0.8 eV for Co2V(Al, Ge, Ga and Si), respectively. The integer amounts of the magnetic moments are compatible with Slater–Pauling role. The optical treatment of Co2VGa is different from three other compounds. All mentioned compounds have metallic behavior by 22 eV plasmonic frequency. The imaginary part of the dielectric function for the up spin indicates that the main optical transitions occurred in this spin mode. Moreover, the elastic results show that the Co2VGa does not have elastic stability, but the other three compounds have fully elastic stability and the Co2V(Al, Ge and Si) belong to the hardness of materials.

A detailed first principle study on the structural, elastic, and electronic properties of indium arsenide (InAs) under induced pressure

2016 ◽  
Vol 94 (3) ◽  
pp. 254-261
Author(s):  
Kh. Kabita ◽  
M. Jameson ◽  
B.I. Sharma ◽  
R.K. Brojen ◽  
R.K. Thapa
Keyword(s):  
Electronic Properties ◽  
Indium Arsenide ◽  
Rock Salt ◽  
Density Functional ◽  
Structural Phase ◽  
Theoretical Data ◽  
Partial Density ◽  
Electronic Band ◽  
Zinc Blende ◽  
Salt Structure

An ab initio calculation of the structural, elastic, and electronic properties of indium arsenide (InAs) under induced pressure is investigated using density functional theory with modified Becke–Johnson potential within the generalised gradient approximation of the Perdew–Burke–Ernzerhof scheme. The lattice parameters are found to be in good agreement with experimental and other theoretical data. The pressure-induced structural phase transition of InAs zinc blende to rock salt structure is found to occur at 4.7 GPa pressure with a 17.2% of volume collapse. The elastic properties of both the zinc blende and rock salt structures at different pressures are studied. The electronic band structures at different pressures for both the structures are investigated using the total and partial density of states. The energy band gap of the InAs zinc blende phase is increased with increasing pressure while in rock salt the phase the conduction band crosses towards the valence band and thus shows metallic behaviour.

First-Principles Calculations of the Structural, Electronic, Optical and Mechanical Properties of CdS, CdSe and CdTe

2013 ◽  
Vol 665 ◽  
pp. 302-306 ◽  
Author(s):  
Sheetal Sharma ◽  
Ajay Singh Verma
Keyword(s):  
Experimental Data ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Zinc Blende ◽  
Optical And Mechanical Properties ◽  
Good Agreement

The structural, electronic, optical and elastic properties of zinc-blende compounds (CdX, X = S, Se and Te), were studied using full-potential augmented plane wave plus local orbitals method (FP-LAPW+ lo) within density functional theory, using generalized gradient approximation (GGA). Geometrical optimization of the unit cell (lattice constant, bulk modulus and its pressure derivative) is in good agreement with experimental data. Results for band structures, density of states, and elastic constants (C11, C12 and C44) are presented. We also report our results on optical properties like the complex dielectric functions and the refractive index (n) of these compounds. Our results are in reasonable agreement with the available theoretical and experimental data.

Computer Simulation of the Magnesium Silicide Polymorphs

2012 ◽  
Vol 170-173 ◽  
pp. 3312-3315
Author(s):  
Dong Chen ◽  
Chao Xu
Keyword(s):  
Optical Properties ◽  
Energy Region ◽  
High Performance ◽  
Density Functional ◽  
High Energy ◽  
Magnesium Silicide ◽  
High Energy Region ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Pseudo Potential

The anti-cotunnite magnesium silicide was constructed, and its absorption coefficient, dielectric function and loss function have been investigated through the plane-wave pseudo- potential calculations based on the density functional theory. In our scheme, we consider the Mg2Si crystal without defects or cracks. Significant features have been observed for the optical properties in the low-energy region and the high-energy region. The main focus of this paper is to determine the high-pressure optical properties of Mg2Si and find out if this material can be used as high-performance thermoelectric devices.

Study on Electronic and Optical Properties of Al-Doped ZnS from Density Function Theory

2013 ◽  
Vol 734-737 ◽  
pp. 2405-2410 ◽  
Author(s):  
Ai Ling Wu ◽  
Li Guan ◽  
Ting Kun Gu ◽  
Pei Yuan Feng
Keyword(s):  
Optical Properties ◽  
Absorption Spectra ◽  
Density Functional ◽  
Systematic Investigation ◽  
Al Doping ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Calculation Results ◽  
Plane Wave Approximation ◽  
Good Agreement

Using ab-initio ultrasoft pseudopotential plane wave approximation method based on density functional theory (DFT), a systematic investigation on electronic and optical properties of ZnS with and without Al-doping has been performed. Calculation results show that Al-doping narrows the band gap of ZnS systems and Al-doped ZnS system changes from semiconductor into metal through the Mott transition. Moreover, with Al-doping increasing, the increase of absorption coefficient and redshift of absorption spectra are obtained. Absorption spectra of pure ZnS and Al-doped ZnS are in good agreement with the experimental results.

Optical properties of arsenic trisulphide

1967 ◽  
Vol 297 (1449) ◽  
pp. 230-243 ◽  
Keyword(s):  
Optical Properties ◽  
Absorption Spectrum ◽  
High Energy ◽  
Refractive Indices ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Axial Angle ◽  
Transmission Measurements ◽  
Additional Maximum ◽  
Good Agreement

The optical absorption spectra ( E || c , E ⊥ c ) of As 2 S 3 have been determined from transmission measurements on single crystals ranging in thickness from 550 to 0·07 μm, At 77 °K the absorption spectrum ( E || c ) consists of three absorption bands A, B and C at 23300, 24100 and 25600 cm -1 respectively. The absorption bands for E ⊥ c occur 500 cm -1 to the high energy side of those for E || c . The variation of absorption coefficient α with photon energy hv at the absorption edge (290°K) can be resolved into four regions each of which is described by the equation α = a ( hv + b ) 2 . At 290 and 77°K the single crystal reflexion spectra ( E || c , E ⊥ c ) show maxima associated with the absorption bands and an additional maximum at 35000 cm -1 . The calculated and measured reflectivities are in good agreement. Measurements have been made of the dispersion of the principal refractive indices and of the optic axial angle. The spectral distribution of photocurrent shows peaks associated with absorption bands B and C ( E || c , E ⊥ c ).

First-principles study of optical properties in Ca-doped ZnO alloys

Open Physics ◽  
2012 ◽  
Vol 10 (5) ◽  
Author(s):  
Li-Na Bai ◽  
Jian-She Lian ◽  
Wei-Tao Zheng ◽  
Qing Jiang
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Optical Transition ◽  
High Energy ◽  
Ternary Alloys ◽  
Potential Candidate ◽  
Coulomb Interactions ◽  
Generalized Gradient ◽  
Light Emitters

AbstractVarious electronic and optical properties of Zn1−x CaxO ternary alloys of wurtzite structure are calculated using a first-principles approach based on the framework of the generalized gradient approximation to density-functional theory. In particular, on-site Coulomb interactions are introduced, which can reasonably well predict the electronic properties and band gaps of the Zn1−x CaxO (0≤x≤0.25) system. The imaginary part of the calculated dielectric function indicates that the optical transition between O 2p states in the valence band and Zn 4s states in the conduction band shifts to the high-energy range as the Ca concentration increases. The calculated band gap shows a significant increase with increasing Ca concentration. Therefore, Zn1−x CaxO ternary alloys may be a potential candidate alloy for optoelectronic materials, and especially for light-emitters and detectors.

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