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

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

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

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1937 ◽  
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.

Indirect-Direct Band Gap Transition by Van Der Waals Interaction Engineering in MoS2/WS2 Bilayer Heterojunction

2014 ◽  
Vol 614 ◽  
pp. 70-74 ◽  
Author(s):  
Hai Ning Cao ◽  
Zhi Ya Zhang ◽  
Ming Su Si ◽  
Feng Zhang ◽  
Yu Hua Wang
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Direct Band Gap ◽  
The Density Functional Theory ◽  
Direct Band ◽  
Electric Filed

First principles calculations based on the density functional theory (DFT) are employed to estimate the electronic structures of bilayer heterostructure of MoS2/WS2. The dependences of the band structures on external electric field and interlayer separation are evaluated. The external electric filed induces a semiconductor-metal transition. At the same time, a larger interlayer separation, corresponding to a weaker interlayer interaction, makes an indirect-direct band gap transition happen for the heterojunction. Our results demonstrate that electronic structure tailoring of two-dimensional layered materials should include both spatial symmetry control and interlayer vdW interactions engineering.

STRUCTURAL PARAMETERS AND OPTOELECTRONIC PROPERTIES OF Mg-IV-V2 (IV=Si, Ge, Sn AND V=P, As) COMPOUNDS

2018 ◽  
Vol 25 (05) ◽  
pp. 1850108 ◽  
Author(s):  
M. IBRAHIM ◽  
HAYAT ULLAH ◽  
SAEED ULLAH JAN ◽  
MANZAR ALI ◽  
M. GULBAHAR ASHIQ
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Structural Parameters ◽  
Visible Region ◽  
Functional Theory ◽  
Lattice Constants ◽  
Direct Band Gap ◽  
Semiconductor Behavior ◽  
Direct Band

Semiconductors are the backbone of the optoelectronic industry. Direct band gap materials in the visible energy region are highly desirable for the efficient optoelectronic applications. In this work, we have probed the structural, electronic and optical properties of Mg-IV-V2 (IV[Formula: see text]Si, Ge, Sn and V[Formula: see text]P, As) compounds by FP-LAPW calculations, based on density functional theory. Their crystal structure is chalcopyrite with space group of I-42d. The lattice constants of MgSiP2, MgSiAs2 and MgGeAs2 are consistent with experimental results. These compounds show semiconductor behavior with direct band gap ranging from 1.3–2.15[Formula: see text]eV. Optical properties were also investigated. Optical properties include real and imaginary parts of dielectric constant, energy loss function, refraction and reflection. Direct band gap nature and good response in the visible region of these compounds predict their usefulness in optoelectronic devices.

Ab initio study of strained wurtzite InAs nanowires: engineering an indirect–direct band gap transition through size and uniaxial strain

RSC Advances ◽  
2015 ◽  
Vol 5 (109) ◽  
pp. 89993-90000 ◽  
Author(s):  
Shweta D. Dabhi ◽  
Prafulla K. Jha
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Band Gap ◽  
Density Functional ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Direct Band Gap ◽  
Inas Nanowires ◽  
Direct Band ◽  
Strain Dependent

Size and strain dependent electronic properties of wurtzite InAs nanowires are investigated using density functional theory.

A New Approach for Calculating the Band Gap of Semiconductors within the Density Functional Method

2015 ◽  
Vol 242 ◽  
pp. 434-439 ◽  
Author(s):  
Vasilii E. Gusakov
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Localized States ◽  
Experimental Accuracy ◽  
Functional Theory ◽  
New Approach ◽  
The Density Functional Theory

Within the framework of the density functional theory, the method was developed to calculate the band gap of semiconductors. We have evaluated the band gap for a number of monoatomic and diatomic semiconductors (Sn, Ge, Si, SiC, GaN, C, BN, AlN). The method gives the band gap of almost experimental accuracy. An important point is the fact that the developed method can be used to calculate both localized states (energy deep levels of defects in crystal), and electronic properties of nanostructures.

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

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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