Electronic structures and elastic properties of monolayer and bilayer transition metal dichalcogenides
 MX
 2
 (
 M
 = Mo, W;
 X
 = O, S, Se, Te): A comparative first-principles study

Zeng, Fanxin; Zhang, Wei-Bing; Tang, Bi‐Yu

doi:10.1088/1674-1056/24/9/097103

Cited by 120 publications

(40 citation statements)

References 32 publications

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“…Apparently, the calculated band gap is 1.79 eV. This is smaller than the previous theoretical value [ 25 ], which is due to different choices of plane-waves cutoff and k-point grid. It is very easy to observe that the conduction band minimum (CBM) and the valence band maximum (VBM) are at the same high symmetry K point, which indicates that monolayer WS 2 is a direct band gap semiconductor that agrees well with the previous calculation.…”

Section: Resultscontrasting

confidence: 59%

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS2: A First-Principles Study

et al. 2018

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Based on the density functional theory (DFT), the electronic properties of O-doped pure and sulfur vacancy-defect monolayer WS2 are investigated by using the first-principles method. For the O-doped pure monolayer WS2, four sizes (2 × 2 × 1, 3 × 3 × 1, 4 × 4 × 1 and 5 × 5 × 1) of supercell are discussed to probe the effects of O doping concentration on the electronic structure. For the 2 × 2 × 1 supercell with 12.5% O doping concentration, the band gap of O-doped pure WS2 is reduced by 8.9% displaying an indirect band gap. The band gaps in 3 × 3 × 1 and 4 × 4 × 1 supercells are both opened to some extent, respectively, for 5.55% and 3.13% O doping concentrations, while the band gap in 5 × 5 × 1 supercell with 2.0% O doping concentration is quite close to that of the pure monolayer WS2. Then, two typical point defects, including sulfur single-vacancy (VS) and sulfur divacancy (V2S), are introduced to probe the influences of O doping on the electronic properties of WS2 monolayers. The observations from DFT calculations show that O doping can broaden the band gap of monolayer WS2 with VS defect to a certain degree, but weaken the band gap of monolayer WS2 with V2S defect. Doping O element into either pure or sulfur vacancy-defect monolayer WS2 cannot change their band gaps significantly, however, it still can be regarded as a potential method to slightly tune the electronic properties of monolayer WS2.

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Section: Resultscontrasting

confidence: 59%

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS2: A First-Principles Study

et al. 2018

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“…Our structural optimizations yield lattice constants 4.08 Å for monolayer InSe and 3.19 Å for monolayer WS 2 . The results are listed in Table 1 and they are in good agreement with the values in previous reports [16,27,31,42,43,44,45]. We build the 2D InSe/WS 2 heterostructure in such a way that the lattice mismatch is made as small as possible and the computational cost is still acceptable at the same time.…”

Section: Computational Methods and Modelssupporting

confidence: 87%

The 2D InSe/WS₂ Heterostructure with Enhanced Optoelectronic Performance in the Visible Region*

Yang¹,

Shi²,

Zhang³

et al. 2019

Chinese Phys. Lett.

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Two-dimensional (2D) InSe and WS 2 exhibit promising characteristics for optoelectronic and photoelectrochemical applications, e.g. photodetection and photocatalytic water splitting. However, both of them have poor absorption of visible light due to wide band gaps. 2D InSe has high electron mobility but low hole mobility, while 2D WS 2 is on the opposite. Here, we design a 2D heterostructure composed of their monolayers and study its optoelectronic properties by first-principles calculations. Our results show that the heterostructure has a direct band gap of 2.19 eV, which is much smaller than those of the monolayers mainly due to a type-II band alignment: the valence band maximum and the conduction band minimum of monolayer InSe are lower than those of monolayer WS 2 , respectively. The visible-light absorption is enhanced considerably, e.g. about fivefold (threefold) increase at the wavelength of 490 nm in comparison to monolayer InSe (WS 2 ). The type-II band alignment also facilitates the spatial separation of photogenerated electron-hole pairs, i.e., electrons (holes) reside preferably in the InSe (WS 2 ) layer. The two layers complement each other in carrier mobilities of the heterostructure: the photogenerated electrons and holes inherit the large mobilities from the InSe and WS 2 monolayers, respectively.

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“…With the lattice constant of WSe 2 (0.328 nm) 2.5% larger than MoS 2 (0.32 nm), the eigenstrain equals 2.5% suggesting that the inclusion is subject to compression. As their elastic properties have been studied (Young's modulus and Poisson's ratio are 270 GPa and 0.24 for MoS 2 , 251.64 GPa and 0.19 for WSe 2 ), the stress or strain state of the heterostructure could be obtained according to Eshelby inclusion theory. The distribution of stress components σ xx and σ xy is plotted in Figure b,c, and their spatial variation along the middle line (marked with the red dashed line in Figure b,c) is plotted in Figure d, the maximum magnitude of which is about 8 GPa.…”

Section: Resutls and Disscusionmentioning

confidence: 99%

In‐Plane Heterostructures Enable Internal Stress Assisted Strain Engineering in 2D Materials

Liu

Wang

Tang

2018

Small

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Conventional methods to induce strain in 2D materials can hardly catch up with the sharp increase in requirements to design specific strain forms, such as the pseudomagnetic field proposed in graphene, funnel effect of excitons in MoS , and also the inverse funnel effect reported in black phosphorus. Therefore, a long-standing challenge in 2D materials strain engineering is to find a feasible scheme that can be used to design given strain forms. In this article, combining the ability of experimentally synthetizing in-plane heterostructures and elegant Eshelby inclusion theory, the possibility of designing strain fields in 2D materials to manipulate physical properties, which is called internal stress assisted strain engineering, is theoretically demonstrated. Particularly, through changing the inclusion's size, the stress or strain gradient can be controlled precisely, which is never achieved. By taking advantage of it, the pseudomagnetic field as well as the funnel effect can be accurately designed, which opens an avenue to practical applications for strain engineering in 2D materials.

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Electronic structures and elastic properties of monolayer and bilayer transition metal dichalcogenides MX ₂ ( M = Mo, W; X = O, S, Se, Te): A comparative first-principles study

Cited by 120 publications

References 32 publications

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS2: A First-Principles Study

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS2: A First-Principles Study

The 2D InSe/WS₂ Heterostructure with Enhanced Optoelectronic Performance in the Visible Region*

In‐Plane Heterostructures Enable Internal Stress Assisted Strain Engineering in 2D Materials

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Electronic structures and elastic properties of monolayer and bilayer transition metal dichalcogenides MX 2 ( M = Mo, W; X = O, S, Se, Te): A comparative first-principles study

Cited by 120 publications

References 32 publications

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS2: A First-Principles Study

The Electronic Properties of O-Doped Pure and Sulfur Vacancy-Defect Monolayer WS2: A First-Principles Study

The 2D InSe/WS2 Heterostructure with Enhanced Optoelectronic Performance in the Visible Region*

In‐Plane Heterostructures Enable Internal Stress Assisted Strain Engineering in 2D Materials

Contact Info

Product

Resources

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Electronic structures and elastic properties of monolayer and bilayer transition metal dichalcogenides MX ₂ ( M = Mo, W; X = O, S, Se, Te): A comparative first-principles study

The 2D InSe/WS₂ Heterostructure with Enhanced Optoelectronic Performance in the Visible Region*