Broadband femtosecond transient absorption spectroscopy for a CVD<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Mo</mml:mi><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>monolayer

Aleithan, Shrouq H.; Livshits, Maksim Y.; Khadka, Sudiksha; Rack, Jeffrey J.; Kordesch, Martin E.; Stinaff, Eric

doi:10.1103/physrevb.94.035445

Cited by 89 publications

(85 citation statements)

References 36 publications

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“…6) to the two contributions distinguished in Ref. 33. Specifically, with our band structure, they arise from particle-hole excitations between approximately parallel bands 3.8 eV apart along the Γ−K and K−M symmetry lines.…”

Section: Nature Of the C Excitonsmentioning

confidence: 58%

“…The optical conductivity, absorption, and reflectance spectra of few and single-layer MoS 2 has been extensively studied in recent experiments 12,[23][24][25][26][27][28][29][30][31][32][33] .…”

Section: Excitons In the Optical Response Of Mos2mentioning

confidence: 99%

“…It is well established that the onset of optical absorption in clean, undoped monolayers occurs at 1.8 ± 0.1 eV, as measured spectroscopically by reflection and photoluminescence 12,23,24,27,31,32 , absorption [26][27][28]33 , photoemission 29 , and second-harmonic analysis 35,38,39 .…”

Section: Excitons In the Optical Response Of Mos2mentioning

confidence: 99%

“…As expected, our calculations agree with previous theoretical works 6,9,10,31,60 that provide a good description of the strongly localized A and B excitons. By using a large sampling of k points in the Brillouin zone we are also able to study the so-called C-exciton 10 and establish its nature, a subject under debate in the literature 10,28,31,33 . The remainder of this paper is organized as follows: In Sec.…”

Section: Introductionmentioning

confidence: 99%

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Excitonic structure of the optical conductivity in MoS2 monolayers

2018

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We investigate the excitonic spectrum of MoS2 monolayers and calculate its optical absorption properties over a wide range of energies. Our approach takes into account the anomalous screening in two dimensions and the presence of a substrate, both cast by a suitable effective Keldysh potential. We solve the Bethe-Salpeter equation using as a basis a Slater-Koster tight-binding model parameterized to fit the ab initio MoS2 band structure calculations. The resulting optical conductivity is in good quantitative agreement with existing measurements up to ultraviolet energies. We establish that the electronic contributions to the C excitons arise not from states at the Γ point, but from a set of k-points over extended portions of the Brillouin zone. Our results reinforce the advantages of approaches based on effective models to expeditiously explore the properties and tunability of excitons in TMD systems.

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Section: Nature Of the C Excitonsmentioning

confidence: 58%

Section: Excitons In the Optical Response Of Mos2mentioning

confidence: 99%

Section: Excitons In the Optical Response Of Mos2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Excitonic structure of the optical conductivity in MoS2 monolayers

2018

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“…It is noteworthy that, the energy of the PL peak does not correspond to that of the A-exciton in the absorption spectra, which is different from previous studies in monolayer TMDs. 16,17 The large deviation between the PL and absorption spectra is likely a signature of the MQD formation. During the synthesis processes, WS 2 nanoflakes are cut into small pieces and produce many defects such as dangle bonds or vacancies at/or near the surface of MQDs.…”

Section: Pl Ple and Absorbance Measurementsmentioning

confidence: 99%

Many-body effects in doped WS2 monolayer quantum disks at room temperature

et al. 2019

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Due to strong Coulomb interactions, reduced screening effects, and quantum confinement, transition-metal dichalcogenide (TMD) monolayer quantum disks (MQDs) are expected to exhibit large exciton binding energy, which is beneficial for the investigation of many-body physics at room temperature. Here, we report the first observations of room-temperature many-body effects in tungsten disulfide (WS 2 ) MQDs by both optical measurements and theoretical studies. The band-gap renormalization in WS 2 MQDs was about 250 ± 15 meV as the carrier density was increased from 0.6(±0.2) × 10 12 to 8.3(±0.2) × 10 12 cm −2 . We observed a striking exciton binding energy as large as 990 ± 30 meV at the lowest carrier density, which is larger than that in WS 2 monolayers. The huge exciton binding energy in WS 2 MQDs is attributed to the extra quantum confinement in the lateral dimension. The band-gap renormalization and exciton binding energies are explained using efficient reduced screening. On the basis of the Debye screening formula, the Mott density in WS 2 MQDs was estimated to be~3.95 × 10 13 cm −2 . Understanding and manipulation of the many-body effects in two-dimensional materials may open up new possibilities for developing exciton-based optoelectronic devices.npj 2D Materials and Applications (2019) 3:46 ; https://doi.

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Emerging Low‐Dimensional Materials for Nonlinear Optics and Ultrafast Photonics

2017

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Low-dimensional (LD) materials demonstrate intriguing optical properties, which lead to applications in diverse fields, such as photonics, biomedicine and energy. Due to modulation of electronic structure by the reduced structural dimensionality, LD versions of metal, semiconductor and topological insulators (TIs) at the same time bear distinct nonlinear optical (NLO) properties as compared with their bulk counterparts. Their interaction with short pulse laser excitation exhibits a strong nonlinear character manifested by NLO absorption, giving rise to optical limiting or saturated absorption associated with excited state absorption and Pauli blocking in different materials. In particular, the saturable absorption of these emerging LD materials including two-dimensional semiconductors as well as colloidal TI nanoparticles has recently been utilized for Q-switching and mode-locking ultra-short pulse generation across the visible, near infrared and middle infrared wavelength regions. Beside the large operation bandwidth, these ultrafast photonics applications are especially benefit from the high recovery rate as well as the facile processibility of these LD materials. The prominent NLO response of these LD materials have also provided new avenues for the development of novel NLO and photonics devices for all-optical control as well as optical circuits beyond ultrafast lasers.

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Broadband femtosecond transient absorption spectroscopy for a CVDMoS2monolayer

Cited by 89 publications

References 36 publications

Excitonic structure of the optical conductivity in MoS2 monolayers

Excitonic structure of the optical conductivity in MoS2 monolayers

Many-body effects in doped WS2 monolayer quantum disks at room temperature

Emerging Low‐Dimensional Materials for Nonlinear Optics and Ultrafast Photonics

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