A first-principles study of the effects of different Al constituents on Ga1−xAlxN nanowires

2016 ◽  
Vol 30 (30) ◽  
pp. 1650217 ◽  
Author(s):  
Sihao Xia ◽  
Lei Liu ◽  
Yike Kong ◽  
Honggang Wang ◽  
Meishan Wang
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Plane Wave ◽  
First Principles ◽  
Formation Energy ◽  
High Energy ◽  
Dielectric Constants ◽  
Interesting Phenomenon ◽  
Densities Of States ◽  
Static Dielectric Constants

In order to investigate the influences of different Al constituents on Ga[Formula: see text]Al[Formula: see text]N nanowires, the formation energy, stability, band structure, densities of states and optical properties of Ga[Formula: see text]Al[Formula: see text]N nanowires with different Al constituents are calculated using first-principles plane-wave ultrasoft pseudopotential method. Results show that Ga[Formula: see text]Al[Formula: see text]N nanowires become more stable with increasing Al constituent. Bandgap of Ga[Formula: see text]Al[Formula: see text]N nanowires increases as the Al constituent increases but with a lower amplification compared with bulk Ga[Formula: see text]Al[Formula: see text]N. The peaks of static dielectric constants show a decreasing trend and move towards high-energy side as Al constituent increases. The absorption of Ga[Formula: see text]Al[Formula: see text]N nanowires shows an interesting phenomenon that it firstly increases and then decreases slightly as the Al constituent increases. Reflectivity of Ga[Formula: see text]Al[Formula: see text]N nanowires is much smaller than that of the bulk. The optical properties of Ga[Formula: see text]Al[Formula: see text]N nanowires show a blueshift effect as Al composition increases. According to these calculations, it is found that Ga[Formula: see text]Al[Formula: see text]N nanowires are appropriate to be applied into photoelectric detecting materials by adjusting the Al constituent of Ga[Formula: see text]Al[Formula: see text]N nanowires.

Exploration on electronic and optical properties of two-dimensional GaN-doped with Be, Mg, Zn

2020 ◽  
Vol 34 (20) ◽  
pp. 2050195
Author(s):  
Gang Li ◽  
Lei Liu ◽  
Jian Tian
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Of States ◽  
First Principles ◽  
High Energy ◽  
Low Energy ◽  
Two Dimensional ◽  
Electronic And Optical Properties ◽  
Type Semiconductor ◽  
P Type

To explore the variation on p-type-doped two-dimensional GaN, we calculate electronic and optical properties of buckled two-dimensional GaN-doped with p-type doping elements including Be, Mg and Zn atom by using first-principles. The results indicate that doping process of two-dimensional GaN after Be is most easily compared with Mg- and Zn-doped models. Band of doped two-dimensional GaN moves toward high energy end and it becomes a p-type semiconductor from the results of band structure and density of states, which may be caused by orbitals hybridization from dopants. Band gap and work function of doped two-dimensional GaN are both declined, which is beneficial for escape of electrons. Analysis of optical properties shows that they are sensitive and adjustable in doped two-dimensional GaN. Doping of Be, Mg and Zn atoms would have an important effect on optical characteristics of two-dimensional GaN at low-energy region.

Full potential linear augmented plane wave calculations of Electronic and Optical properties in ZnO

2016 ◽  
pp. 3298-3311
Author(s):  
M. Benkraouda ◽  
N. Amrane
Keyword(s):  
Zinc Oxide ◽  
Optical Properties ◽  
Band Structure ◽  
Plane Wave ◽  
Density Functional ◽  
Dielectric Constants ◽  
Oxide Semiconductor ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Electronic And Optical Properties

          In this work we present self-consistent calculations for the electronic and optical properties of Zinc oxide. A theoretical investigation of the electronic properties (band structure, density of charge and contour map) and optical properties (refractive index, absorption coefficient, dielectric constants and reflectivity) of Zinc oxide semiconductor ZnO. A full-potential linearized augmented plane-wave (FPLAPW) method was used within the density functional theory (DFT) along with the generalized gradient approximation (GGA96) exchange correlation potential. The results are compared with the experimental data available and some other theoretical work. We found that the GGA approximation yields only a small improvement to the band gap, however, if we allow for a rigid shift of the band structure, the so-called scissor’s operator, the optical properties are excellently reproduced.

First-Principles Calculations on Structural, Electronic, and Optical Properties of 2H-CuAlO2

2011 ◽  
Vol 197-198 ◽  
pp. 487-490 ◽  
Author(s):  
Li Ping Feng ◽  
Zheng Tang Liu ◽  
Qi Jun Liu
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Structure ◽  
First Principles ◽  
Density Functional ◽  
Lattice Parameters ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Charge Densities ◽  
Densities Of States

Structural, electronic and optical properties of 2H-CuAlO2 were computed, using the plane-wave ultrasoft pseudopotential technique based on the first-principles density functional theory (DFT). The equilibrium lattice parameters, band structure, densities of states (DOS) and charge densities of 2H-CuAlO2 have been obtained. The equilibrium lattice parameters, band structure and DOS are found to be in good agreement with the available experimental and calculational values. The charge densities and the chemical bonding of 2H-CuAlO2 are analyzed, which show that bonding between Cu and O is mainly covalent due to Cu 3d and O 2p hybridization and that bonding between Al and O is mainly ionic. The complex dielectric function, refractive index and absorption coefficient of 2H-CuAlO2 have been predicted. The calculated static dielectric constant and static refractive index of 2H-CuAlO2 is 7.1 and 2.66, respectively.

ELECTRONIC STRUCTURES AND OPTICAL PROPERTIES OF 2Al- and 2Ca-DOPED β-Si3N4: A FIRST-PRINCIPLES STUDY

2012 ◽  
Vol 27 (04) ◽  
pp. 1250212 ◽  
Author(s):  
XUEFENG LU ◽  
PEIQING LA ◽  
XIN GUO ◽  
YUPENG WEI ◽  
XUELI NAN ◽  
...  
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Dielectric Constants ◽  
Absorption Bands ◽  
Two Systems ◽  
Potential Applications ◽  
Electron Energy Loss ◽  
Static Dielectric Constants ◽  
Formation Energies

First-principles calculations have been conducted to study the electronic structures and optical properties of 2 Al - and 2 Ca -doped β- Si 3 N 4. Calculated formation energies of 2 Al - and 2 Ca -doped systems are 5.9745 eV and 18.9376 eV, respectively, indicating the former has a stable structure than the latter. The band gaps of two systems are 3.1573 eV and 2.0155 eV, respectively, reveals that the band structures of them behave like semiconductors. The static dielectric constants of two systems are 40 and 37, respectively, which denotes their potential applications in electronics and optics. The strong absorption bands ranging from 4 eV to 16 eV become much sharper and show a red-shift after doping. The offset of 2Al -doped system is larger than that of 2Ca -doped system. The absorption coefficient can be remarkably modulated by doping. In calculated frequency-dependent electron energy loss spectra (EELS) of doping systems, the host peaks all locate at about 15 eV.

scholarly journals Electronic and optical properties of vacancy ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; and X = Cl, Br, I): a first principles study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Faizan ◽  
K. C. Bhamu ◽  
Ghulam Murtaza ◽  
Xin He ◽  
Neeraj Kulhari ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Perovskite Solar Cells ◽  
Dielectric Constants ◽  
Maximum Efficiency ◽  
Exchange Potential ◽  
Double Perovskites ◽  
Electronic And Optical Properties

AbstractThe highly successful PBE functional and the modified Becke–Johnson exchange potential were used to calculate the structural, electronic, and optical properties of the vacancy-ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; X = Cl, Br, and I) using the density functional theory, a first principles approach. The convex hull approach was used to check the thermodynamic stability of the compounds. The calculated parameters (lattice constants, band gap, and bond lengths) are in tune with the available experimental and theoretical results. The compounds, Rb2PdBr6 and Cs2PtI6, exhibit band gaps within the optimal range of 0.9–1.6 eV, required for the single-junction photovoltaic applications. The photovoltaic efficiency of the studied materials was assessed using the spectroscopic-limited-maximum-efficiency (SLME) metric as well as the optical properties. The ideal band gap, high dielectric constants, and optimum light absorption of these perovskites make them suitable for high performance single and multi-junction perovskite solar cells.

scholarly journals Accurate Prediction of Band Structure of FeS2: A Hard Quest of Advanced First-Principles Approaches

2021 ◽  
Vol 9 ◽  
Author(s):  
Min-Ye Zhang ◽  
Hong Jiang
Keyword(s):  
Band Structure ◽  
First Principles ◽  
High Energy ◽  
Accurate Prediction ◽  
Band Gaps ◽  
Full Potential ◽  
Band Structures ◽  
Electronic Band ◽  
Fundamental Band ◽  
Hybrid Functionals

The pyrite and marcasite polymorphs of FeS2 have attracted considerable interests for their potential applications in optoelectronic devices because of their appropriate electronic and optical properties. Controversies regarding their fundamental band gaps remain in both experimental and theoretical materials research of FeS2. In this work, we present a systematic theoretical investigation into the electronic band structures of the two polymorphs by using many-body perturbation theory with the GW approximation implemented in the full-potential linearized augmented plane waves (FP-LAPW) framework. By comparing the quasi-particle (QP) band structures computed with the conventional LAPW basis and the one extended by high-energy local orbitals (HLOs), denoted as LAPW + HLOs, we find that one-shot or partially self-consistent GW (G0W0 and GW0, respectively) on top of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation with a converged LAPW + HLOs basis is able to remedy the artifact reported in the previous GW calculations, and leads to overall good agreement with experiment for the fundamental band gaps of the two polymorphs. Density of states calculated from G0W0@PBE with the converged LAPW + HLOs basis agrees well with the energy distribution curves from photo-electron spectroscopy for pyrite. We have also investigated the performances of several hybrid functionals, which were previously shown to be able to predict band gaps of many insulating systems with accuracy close or comparable to GW. It is shown that the hybrid functionals considered in general fail badly to describe the band structures of FeS2 polymorphs. This work indicates that accurate prediction of electronic band structure of FeS2 poses a stringent test on state-of-the-art first-principles approaches, and the G0W0 method based on semi-local approximation performs well for this difficult system if it is practiced with well-converged numerical accuracy.

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).

THE EFFECT OF HIGH N-DOPED ANATASE TiO2 ON THE BAND GAP NARROWING AND REDSHIFT BY FIRST-PRINCIPLES

2012 ◽  
Vol 26 (27) ◽  
pp. 1250179 ◽  
Author(s):  
QINGYU HOU ◽  
YONGJUN JIN ◽  
CHUN YING ◽  
ERJUN ZHAO ◽  
YUE ZHANG ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Formation Energy ◽  
Doping Concentration ◽  
Covalent Bond ◽  
Anatase Tio2 ◽  
Structure Population ◽  
Densities Of States ◽  
N Doping ◽  
Band Gap Narrowing

Anatase TiO 2 supercells were studied by first-principles, in which one was undoped and another three were high N -doping. Partial densities of states, band structure, population and absorption spectrum were calculated. The calculated results indicated that in the condition of TiO 2-x N x (x = 0.0625, 0.125, 0.25), the higher the doping concentration is, the shorter will be the lattice parameters parallel to the direction of c-axis. The strength of covalent bond significantly varied. The formation energy increases at first, and then decreases. The doping models become less stable as N -doping concentration increases. Meanwhile, the narrower the band gap is, the more significant will be the redshift, which is in agreement with the experimental results.

Bandgap control and optical properties of β-Si3N4 by single- and co-doping from a first-principles simulation

2018 ◽  
Vol 32 (14) ◽  
pp. 1850178 ◽  
Author(s):  
Xuefeng Lu ◽  
Xu Gao ◽  
Junqiang Ren ◽  
Cuixia Li ◽  
Xin Guo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Blue Shift ◽  
Functional Theory ◽  
Co Doping ◽  
Charge Density Difference ◽  
Co Doped

Bandgap tailoring of [Formula: see text]-Si3N4 is performed by single and co-doping by using density functional theory (DFT) of PBE functional and plane-wave pseudopotential method. The results reveal that a direct bandgap transfers into an indirect one when single-doped with As element. Also, a considerate decrease of bandgap to 0.221 eV and 0.315 eV is present for Al–P and As–P co-doped systems, respectively, exhibiting a representative semiconductor property that is characteristic for a narrower bandgap. Compared with other doped systems, Al-doped system with formation energy of 2.67 eV is present for a more stable structure. From charge density difference (CDD) maps, it is found that the blue area between co-doped atoms increases, illustrating an enhancement of covalent property for Al–P and Al–As bonds. Moreover, a slightly obvious “Blue shift” phenomenon can be obtained in Al, Al–P and Al–As doped systems, indicating an enhanced capacity of responses to light, which contributes to the insight for broader applications with regard to photoelectric devices.

First-principles calculations of the structural, elastic, mechanical, electronic and optical properties of monoclinic Hf4CuSi4

2020 ◽  
Vol 34 (06) ◽  
pp. 2050035
Author(s):  
Xia Xu ◽  
Wei Zeng ◽  
Fu-Sheng Liu ◽  
Zheng-Tang Liu ◽  
Qi-Jun Liu
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Elastic Anisotropy ◽  
Structural Parameters ◽  
Functional Theory ◽  
Text Structures ◽  
Structure Density

In this paper, the structural, electronic, elastic, mechanical and optical properties of monoclinic [Formula: see text] are studied using the first-principles density functional theory (DFT). The calculated structural parameters are consistent with the experimental data. The elastic constants of [Formula: see text] structures are calculated, indicating that [Formula: see text] shows mechanical stability and elastic anisotropy. According to the [Formula: see text] and Poisson’s ratio, monoclinic [Formula: see text] shows a brittle manner. The energy band structure, density of states, charge transfers and bond populations are given. And the band structure shows that the material is a metal conductor. Moreover, the optical properties and optical anisotropy of [Formula: see text] are shown and analyzed.

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