Study of the layer-dependent properties of MoS<sub>2</sub> nanosheets with different crystal structures by DFT calculations

Zhao, Zong‐Yan; Liu, Qing-Lu

doi:10.1039/c7cy02252b

Cited by 109 publications

(57 citation statements)

References 52 publications

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“…The band formation of ReS 2 is constructed by the references 42,43 . The measured DT/FN barrier heights are higher than the prediction of Schottky-type barrier due to interfacial band alignment 42,[44][45][46] . Due to the abundant intrinsic sulfur vacancies of the 1L MoS 2 , the Fermi level is close to the conduction band minimum 47,48 , hence the lowest potential difference between forward bias and reverse bias is close 0 eV, due to the highly symmetric I-V behaviors (Fig.…”

Section: Discussionmentioning

confidence: 56%

Site-specific electrical contacts with the two-dimensional materials

et al. 2020

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Electrical contact is an essential issue for all devices. Although the contacts of the emergent two-dimensional materials have been extensively investigated, it is still challenging to produce excellent contacts. The face and edge type contacts have been applied previously, however a comparative study on the site-specific contact performances is lacking. Here we report an in situ transmission electron microscopy study on the contact properties with a series of 2D materials. By manipulating the contact configurations in real time, it is confirmed that, for 2D semiconductors the vdW type face contacts exhibit superior conductivity compared with the non-vdW type contacts. The direct quantum tunneling across the vdW bonded interfaces are virtually more favorable than the Fowler-Nordheim tunneling across chemically bonded interfaces for contacts. Meanwhile, remarkable area, thickness, geometry, and defect site dependences are revealed. Our work sheds light on the significance of contact engineering for 2D materials in future applications.

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Section: Discussionmentioning

confidence: 56%

Site-specific electrical contacts with the two-dimensional materials

et al. 2020

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“…In general, the linear absorption increases as the sample thickness is enlarged, according to Beer–Lambert law (i.e., where T is the transmittance, α is the absorption coefficient, and d is the sample thickness). The sample-thickness-dependent property variations have been reported for various saturable absorption materials such as TIs, TMDCs, and BP 84 – 89 . The bandgap energies of the materials are known to change depending on the layer number.…”

Section: Resultsmentioning

confidence: 99%

Nonlinear optical properties of arsenic telluride and its use in ultrafast fiber lasers

Lee

Jhon

Lee

et al. 2020

Sci Rep

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We report the first investigation results of the nonlinear optical properties of As2Te3. More specifically, the nonlinear optical absorption properties of the prepared α-As2Te3 were investigated at wavelengths of 1.56 and 1.9 μm using the open-aperture (OA) Z-scan technique. Using the OA Z-scan technique, the nonlinear absorption coefficients (β) of α-As2Te3 were estimated in a range from (− 54.8 ± 3.4) × 104 cm/GW to (− 4.9 ± 0.4) × 104 cm/GW depending on the irradiance of the input beam at 1.56 μm, whereas the values did from (− 19.8 ± 0.8) × 104 cm/GW to (− 3.2 ± 0.1) × 104 cm/GW at 1.9 μm. In particular, the β value at 1.56 μm is an order of magnitude larger than the previously reported values of other group-15 sesquichalcogenides such as Bi2Se3, Bi2Te3, and Bi2TeSe2. Furthermore, this is the first time report on β value of a group-15 sesquichalcogenide at a 1.9-μm wavelength. The density functional theory (DFT) calculations of the electronic band structures of α-As2Te3 were also conducted to obtain a better understanding of their energy band structure. The DFT calculations indicated that α-As2Te3 possess sufficient optical absorption in a wide wavelength region, including 1.5 μm, 1.9 μm, and beyond (up to 3.7 μm). Using both the measured nonlinear absorption coefficients and the theoretically obtained refractive indices from the DFT calculations, the imaginary parts of the third-order optical susceptibilities (Im χ(3)) of As2Te3 were estimated and they were found to vary from (− 39 ± 2.4) × 10–19 m2/V2 to (− 3.5 ± 0.3) × 10–19 m2/V2 at 1.56 μm and (− 16.5 ± 0.7) × 10–19 m2/V2 to (− 2.7 ± 0.1) × 10–19 m2/V2 at 1.9 μm, respectively, depending on the irradiance of the input beam. Finally, the feasibility of using α-As2Te3 for SAs was investigated, and the prepared SAs were thus tested by incorporating them into an erbium (Er)-doped fiber cavity and a thulium–holmium (Tm–Ho) co-doped fiber cavity for both 1.5 and 1.9 μm operation.

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“…MoS 2 mainly has three possible polymorphs, including 1T′‐MoS 2 (space group of P 2 1 / m ), 2H‐MoS 2 (space group of P 6 3 / mmc ) and 3R‐MoS 2 (space group of R 3 m ). [ 97 ] The 2H‐MoS 2 phase with larger binding energy was regarded as a thermodynamically stable semiconductor, while 1T′‐MoS 2 and 3R‐MoS 2 were common intermediate phase and possessed metallic characteristics. In general, the crystal structure of MoS 2 is composed of stacked sandwich‐like S‐Mo‐S layers, in which the layers are correlated by the weak van der Waals interaction.…”

Section: Binary Metal Sulfide Photocatalystsmentioning

confidence: 99%

Nanostructured Metal Sulfides: Classification, Modification Strategy, and Solar‐Driven CO₂ Reduction Application

Wang

Lin

Tian

et al. 2020

Adv Funct Materials

271

170

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Solar‐driven conversion of CO2 into high value‐added fuels is expected to be an environmental‐friendly and sustainable approach for relieving the greenhouse gas effect and countering energy crisis. Metal sulfide semiconductors with wide photoresponsive range and favorable band structures are suitable photocatalysts for CO2 photoreduction. This review summarizes the recent progress on metal sulfide semiconductors for photocatalytic CO2 reduction. First, the fundamentals, mechanisms and some principles, like product selectivity, of photocatalytic CO2 reduction are introduced. Then, according to the elemental composition, the metal sulfide photocatalysts applied for CO2 reduction are classified into binary (CdS, ZnS, MoS2, SnS2, Bi2S3, In2S3,Cu2S, NiS/NiS2, and CoS2), ternary (ZnIn2S4, CdIn2S4, CuInS2, Cu3SnS4, and CuGaS2), and quaternary (Cu2ZnSnS4) systems, in which their crystal structures, photochemical characteristics, and photocatalytic CO2 reduction applications are systematically demonstrated. Especially, the diverse modification strategies for improving the activity and product selectivity of photocatalytic CO2 reduction on these metal sulfides are summarized. Finally, the current challenges and future directions for the development of metal sulfide photocatalysts for CO2 reduction are proposed. This review is expected to serve as a powerful reference for exploiting high‐efficiency metal sulfide photocatalysts for CO2 conversion and furthering related mechanism understanding.

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Study of the layer-dependent properties of MoS₂ nanosheets with different crystal structures by DFT calculations

Cited by 109 publications

References 52 publications

Site-specific electrical contacts with the two-dimensional materials

Site-specific electrical contacts with the two-dimensional materials

Nonlinear optical properties of arsenic telluride and its use in ultrafast fiber lasers

Nanostructured Metal Sulfides: Classification, Modification Strategy, and Solar‐Driven CO₂ Reduction Application

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Study of the layer-dependent properties of MoS2 nanosheets with different crystal structures by DFT calculations

Cited by 109 publications

References 52 publications

Site-specific electrical contacts with the two-dimensional materials

Site-specific electrical contacts with the two-dimensional materials

Nonlinear optical properties of arsenic telluride and its use in ultrafast fiber lasers

Nanostructured Metal Sulfides: Classification, Modification Strategy, and Solar‐Driven CO2 Reduction Application

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Study of the layer-dependent properties of MoS₂ nanosheets with different crystal structures by DFT calculations

Nanostructured Metal Sulfides: Classification, Modification Strategy, and Solar‐Driven CO₂ Reduction Application