Strain and Electric Field Modulated Indirect to Direct Band Transition of Monolayer GaInS2

Abstract Strain and electric field dependent electronic and optical properties have been calculated using density functional theory (DFT) and time-dependent DFT (TD-DFT) for GaInS2 monolayer. GaInS2 monolayer shows an indirect band gap of 1.79 eV where valance band maxima (VBM) and conduction band maxima (CBM) rest between K and Γ point and at Γ point, respectively. Under a particular tensile strain (8%), a phase change from semiconductor to semimetal has been noticed. While at 4% compressive strain, the material changes from indirect to direct band gap of 2.22 eV having VBM and CBM at Γ point. With further increase in compressive strain, CBM shifted from Γ to M point, which leads to an indirect band gap again. The electric field also affects the band structure of monolayer GaInS2 and shows the transition between indirect to direct band gap at positive electric field of 4 V/nm, which acts normal to the surface. The strain-dependent optical properties are also calculated, which suggests that the absorption coefficient increases with compressive strain.

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Stable GaSe-Like Phosphorus Carbide Monolayer with Tunable Electronic and Optical Properties from Ab Initio Calculations

Materials ◽

10.3390/ma11101937 ◽

2018 ◽

Vol 11 (10) ◽

pp. 1937 ◽

Cited By ~ 5

Author(s):

Xiaolin Cai ◽

Zhili Zhu ◽

Weiyang Yu ◽

Chunyao Niu ◽

Jianjun Wang ◽

...

Keyword(s):

Optical Properties ◽

Band Gap ◽

Electronic Structures ◽

Density Functional ◽

Promising Candidate ◽

Functional Theory ◽

Electronic And Optical Properties ◽

Direct Band Gap ◽

Direct Band ◽

Indirect Band Gap

On the basis of density functional theory (DFT) calculations, we propose a stable two-dimensional (2D) monolayer phosphorus carbide (PC) with a GaSe-like structure, which has intriguing electronic and optical properties. Our calculated results show that this 2D monolayer structure is more stable than the other allotropes predicted by Tománek et al. [Nano Lett., 2016, 16, 3247–3252]. More importantly, this structure exhibits superb optical absorption, which can be mainly attributed to its direct band gap of 2.65 eV. The band edge alignments indicate that the 2D PC monolayer structure can be a promising candidate for photocatalytic water splitting. Furthermore, we found that strain is an effective method used to tune the electronic structures varying from direct to indirect band-gap semiconductor or even to metal. In addition, the introduction of one carbon vacancy in such a 2D PC structure can induce a magnetic moment of 1.22 µB. Our findings add a new member to the 2D material family and provide a promising candidate for optoelectronic devices in the future.

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SHIFT OF BAND GAP FROM DIRECT TO INDIRECT AND OPTICAL RESPONSE OF LiF UNDER PRESSURE

Modern Physics Letters B ◽

10.1142/s0217984913500619 ◽

2013 ◽

Vol 27 (09) ◽

pp. 1350061 ◽

Cited By ~ 12

Author(s):

A. SAJID ◽

G. MURTAZA ◽

A. H. RESHAK

Keyword(s):

Refractive Index ◽

Optical Properties ◽

Band Gap ◽

Lithium Fluoride ◽

Pressure Range ◽

Pressure Effect ◽

Indirect Transition ◽

Direct Band Gap ◽

Direct Band ◽

Indirect Band Gap

We hereby are reporting the transition pressure at which lithium fluoride ( LiF ) compound transforms from direct band gap to indirect band gap insulator on the basis of FP-LAPW calculations. The fundamental band gap of LiF compound suffers direct to indirect transition at a pressure of 70 GPa. The study of the pressure effect on the optical properties e.g. dielectric function, reflectivity, refractive index and optical conductivity of LiF in the pressure between 0–100 GPa, shows that this pressure range is very critical for LiF compound as there are significant changes in the optical properties of this compound.

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The effects of Sc doping and O vacancy on the electronic states and optical properties of m-BiVO4

Canadian Journal of Physics ◽

10.1139/cjp-2020-0284 ◽

2020 ◽

Author(s):

Yuhong Huang ◽

Xiaqing Zhang ◽

Jingnan Wang ◽

Jianmin Zhang ◽

Xiumei Wei ◽

...

Keyword(s):

Optical Properties ◽

Oxygen Vacancy ◽

Band Gap ◽

Density Functional ◽

Electronic States ◽

Dft Method ◽

Defect Concentration ◽

Direct Band Gap ◽

Direct Band ◽

The Ideal

Based on density functional theory (DFT), the effects of scandium (Sc) doping and oxygen vacancy (VO) on the electronic states and optical properties of BiVO4 are investigated. GGA+U method is adopt during the calculation of the electronic properties to compensate the limitation of DFT method. The ideal BiVO4 has a direct band gap of 2.400 eV, and if Bi in BiVO4 is substituted by Sc (sub Sc-Bi), the direct band gap will be reduced to 2.393 eV. However, if V is replaced by Sc (sub Sc-V) as well as that with oxygen vacancy induced (sub Sc-V+Vo), the band gap will become indirect one with values of 1.913 eV and 2.198 eV, respectively. The reduction capability is in the sequence of sub Sc-Bi > ideal > sub Sc-V+Vo > sub Sc-V, while the oxidation capability is in the order of ideal > sub Sc-Bi > sub Sc-V+Vo > sub Sc-V. The ε<sub>1</sub> (0) of the ideal, sub Sc-Bi, subSc-V and sub Sc-V+Vo defective BiVO4 is 8.290, 8.293, 12.791 and 8.285, respectively. The optical absorptions of ideal and sub Sc-Bi BiVO4 show anisotropy and they are nearly independent on the defect concentration. Sub Sc-V BiVO4 exhibits stronger absorption than the other three semiconductors. The absorptions of sub Sc-V+Vo BiVO4 vary obviously with the defect concentrations, where 3.906% defect concentration of BiVO4 has the strongest absorptions. The estimated optical band gaps are smaller than for ideal and defective BiVO4.

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Electronic State and Piezoresistivity Analysis of Zinc Oxide Nanowires for Force Sensing Devices

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.644.16 ◽

2015 ◽

Vol 644 ◽

pp. 16-21 ◽

Cited By ~ 2

Author(s):

Koichi Nakamura

Keyword(s):

Band Gap ◽

Compressive Strain ◽

Force Sensing ◽

Wall Structure ◽

Direct Band Gap ◽

Direct Band ◽

The Difference ◽

Piezoresistance Coefficient ◽

Indirect Band Gap ◽

P Type

The piezoresistivity for force sensing in wurtzite-ZnO nanowires with [0001] orientation has been simulated on the basis of the first-principles calculations of model structures. According to the difference in wall structure, our devised nanowire models can be divided into three groups by their conductivities; no band-gap conducting models, direct band-gap semiconducting models, and indirect band-gap semiconducting models. The strain responses to carrier conductivity of n-or p-doped semiconducting wurtzite-ZnO[0001] nanowire models were calculated using band carrier densities and their corresponding effective masses derived from the one-dimensional band diagram by our original procedure for a small amount of carrier occupation. The conductivities of p-type direct band-gap models change drastically due to longitudinal uniaxial strain in the simulation: the longitudinal piezoresistance coefficient is 120 × 10–11 Pa–1 for p-type (ZnO)24 nanowire model with 1% compressive strain at room temperature.

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Strain-tunable electronic structure of two-dimensional monolayer SiP

Modern Physics Letters B ◽

10.1142/s0217984921504042 ◽

2021 ◽

pp. 2150404

Author(s):

Xiao Han ◽

Fan-Shun Meng ◽

Xiao-Jie Yan ◽

Hui Zhang

Keyword(s):

Electronic Structure ◽

Band Gap ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Honeycomb Lattice ◽

Application Range ◽

Direct Band Gap ◽

Direct Band ◽

Indirect Band Gap ◽

Armchair Direction

The 2D monolayer [Formula: see text]-SiP has a honeycomb lattice and an intrinsic indirect band gap. Herein, the density functional theory calculations are performed to modulate the electronic structure of 2D monolayer [Formula: see text]-SiP by applying strains. The band gap of monolayer [Formula: see text]-SiP is monotonously reduced by the strains. More interestingly, a direct band gap is more likely to be achieved by applying strains along the armchair direction than along the zigzag direction. Finally, 2D monolayer [Formula: see text]-SiP can possess a tunable direct band gap of 1.57–0.73 eV (HSE06) and considerable visible light absorption index, by applying compression strains of −6–−10% along the armchair direction. The work provides a route of modulating the electronic and optical properties of monolayer [Formula: see text]-SiP, which extends its application range for various fields such as electronic devices and solar energy conversion.

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Electronic structures and optical properties of IV A elements-doped 3C-SiC from density functional calculations

Modern Physics Letters B ◽

10.1142/s021798491850389x ◽

2018 ◽

Vol 32 (32) ◽

pp. 1850389 ◽

Cited By ~ 4

Author(s):

Xuefeng Lu ◽

Tingting Zhao ◽

Xin Guo ◽

Meng Chen ◽

Junqiang Ren ◽

...

Keyword(s):

Optical Properties ◽

Band Gap ◽

Electronic Structures ◽

Density Functional ◽

Visible Region ◽

First Principles Calculation ◽

Charge Difference Density ◽

Direct Band ◽

Density Analysis ◽

Indirect Band Gap

Electronic structures and optical properties of IV A elements (Ge, Sn and Pb)-doped 3C-SiC are investigated by means of the first-principles calculation. The results reveal that the structure of Ge-doped system is more stable with a lower formation energy of 1.249 eV compared with those of Sn- and Pb-doped 3C-SiC systems of 3.360 eV and 5.476 eV, respectively. Doping of the IV A elements can increase the band gap, and there is an obvious transition from an indirect band gap to a direct band gap. Furthermore, charge difference density analysis proves that the covalent order of bonding between the doping atoms and the C atoms is Ge–C [Formula: see text] Sn–C [Formula: see text] Pb–C, which is fully verified by population values. Due to the lower static dielectric constant, the service life of 3C-SiC dramatically improved in production practice. Moreover, the lower reflectivity and absorption peak in the visible region, implying its wide application foreground in photoelectric devices.

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Indirect-to-Direct Band Gap Transition and Optical properties of Cs2BiAgX6 with Mechanical Strains: The Density Functional Theory Investigation

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2021.12.138 ◽

2022 ◽

Author(s):

Xiao Zhang ◽

Yuanyuan Lv ◽

Yuzhuo Lv ◽

Yanbing Liu ◽

Zhenqing Yang

Keyword(s):

Density Functional Theory ◽

Optical Properties ◽

Band Gap ◽

Density Functional ◽

Functional Theory ◽

Direct Band Gap ◽

The Density Functional Theory ◽

Direct Band

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DFT Study on Structural, Electronic and Optical Properties of Ag-Doped SrTiO3 Perovskite for Optoelectronic Applications

10.22541/au.162211054.44550162/v1 ◽

2021 ◽

Author(s):

Jalil Rehman ◽

M.Awais Rehman ◽

Muhammad Bilal Tahir ◽

Muhammad Usman ◽

Faisal Iqbal

Keyword(s):

Optical Properties ◽

Band Gap ◽

Density Of States ◽

Density Functional ◽

Partial Density ◽

Electronic Band ◽

Ag Doping ◽

Direct Band Gap ◽

Direct Band ◽

Optoelectronic Applications

This study addresses the first-principles analysis using generalized gradient approximation (GGA), which is pillared on density functional theory (DFT), to find the effects of silver (Ag) doping on SrTiO3 structurally, electronically and optical properties. As Ag doping into SrTiO3, we see a small decrease in the volume of unit cell. Moreover, Ag-doping adds new states in SrTiO3 at Brillouin zone symmetry points, transferring host material’s indirect band gap to a direct band gap. Ag doping in SrTiO3 results in the transfer density of states to smaller energies and increase in interaction among Ag atom and its surrounding atoms. Moreover, at the conduction band, the partial density of states (PDOS) of SrTiO3 changes generally. As a result, we conclude that Ag doping has an effect on the electronic band structure of SrTiO3. SrTiO3 doping with Ag has improved optical properties and its ability of converting to direct band gap results it in a perfect choice for optoelectronic applications.

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First-principles studies of pure and fluorine substituted alanines

International Journal of Modern Physics B ◽

10.1142/s021797921650079x ◽

2016 ◽

Vol 30 (14) ◽

pp. 1650079 ◽

Cited By ~ 5

Author(s):

Sardar Ahmad ◽

Hamide Vaizie ◽

H. A. Rahnamaye Aliabad ◽

Rashid Ahmad ◽

Imad Khan ◽

...

Keyword(s):

Optical Properties ◽

Band Gap ◽

Density Functional ◽

Structural Parameters ◽

Wide Band ◽

Electromagnetic Spectrum ◽

Orthorhombic Crystal ◽

Orthorhombic Crystal Structure ◽

Direct Band ◽

Indirect Band Gap

This paper communicates the structural, electronic and optical properties of L-alanine, monofluoro and difluoro substituted alanines using density functional calculations. These compounds exist in orthorhombic crystal structure and the calculated structural parameters such as lattice constants, bond angles and bond lengths are in agreement with the experimental results. L-alanine is an indirect band gap insulator, while its fluorine substituted compounds (monofluoroalanine and difluoroalanine) are direct band gap insulators. The substitution causes reduction in the band gap and hence these optically tailored direct wide band gap materials have enhanced optical properties in the ultraviolet (UV) region of electromagnetic spectrum. Therefore, optical properties like dielectric function, refractive index, reflectivity and energy loss function are also investigated. These compounds have almost isotropic nature in the lower frequency range while at higher energies, they have a significant anisotropic nature.

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