Giant Stark splitting of an exciton in bilayer MoS2

Leisgang, Nadine; Shree, Shivangi; Paradisanos, Ioannis; Sponfeldner, Lukas; Robert, Cédric; Lagarde, Delphine; Balocchi, Andréa; Watanabe, Kenji; Taniguchi, Takashi; Marie, X.; Warburton, Richard J.; Gerber, Iann C.; Urbaszek, B.

doi:10.1038/s41565-020-0750-1

Cited by 110 publications

(133 citation statements)

References 36 publications

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“…SHG in MoS 2 bilayers on SiO 2 /Si. Very recently, details of the rich excitonic resonances in bilayer MoS 2 have been uncovered 41 . We aim to distinguish the possible SHG generation that comes from a weak, intrinsic, crystal-related contribution from the possible excitonic contribution by using a tunable laser source.…”

Section: Resultsmentioning

confidence: 99%

“…2a-c results for hBN-encapsulated mono-, bi-, and trilayers, for the same sample used in ref. 41 . Our aim is to compare the surprising SHG amplitude for bilayers with the monolayer and trilayers, for which crystal inversion symmetry is broken and as a consequence strong SHG is expected 33 .…”

Section: Resultsmentioning

confidence: 99%

“…In this work we demonstrate strong, tunable SHG based on exciton resonances in nominally inversion-symmetric MoS 2 bilayers with 2H stacking: Varying the laser excitation energy allows us to address resonantly not only intralayer and but also interlayer exciton states with large oscillator strength 41 , which makes MoS 2 bilayers particularly interesting. At these specific energies we generate SHG signals in MoS 2 bilayers which are (i) comparable in amplitude to off-resonance SHG monolayer signals and (ii) several orders of magnitude larger than reported in the literature for TMD bilayers with 2H stacking 33,38,42,43 .…”

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confidence: 87%

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Interlayer exciton mediated second harmonic generation in bilayer MoS2

et al. 2021

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Second-harmonic generation (SHG) is a non-linear optical process, where two photons coherently combine into one photon of twice their energy. Efficient SHG occurs for crystals with broken inversion symmetry, such as transition metal dichalcogenide monolayers. Here we show tuning of non-linear optical processes in an inversion symmetric crystal. This tunability is based on the unique properties of bilayer MoS2, that shows strong optical oscillator strength for the intra- but also interlayer exciton resonances. As we tune the SHG signal onto these resonances by varying the laser energy, the SHG amplitude is enhanced by several orders of magnitude. In the resonant case the bilayer SHG signal reaches amplitudes comparable to the off-resonant signal from a monolayer. In applied electric fields the interlayer exciton energies can be tuned due to their in-built electric dipole via the Stark effect. As a result the interlayer exciton degeneracy is lifted and the bilayer SHG response is further enhanced by an additional two orders of magnitude, well reproduced by our model calculations. Since interlayer exciton transitions are highly tunable also by choosing twist angle and material combination our results open up new approaches for designing the SHG response of layered materials.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 87%

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Interlayer exciton mediated second harmonic generation in bilayer MoS2

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“…[29] Using high electric fields the Stark effect supports energetic tuning of inter-layer excitons up to 120 meV in MoS 2 bilayers, bringing intra and inter-layer excitons into resonance. [30] Tuning the carrier density in 2D materials can be used to tailor the coupling between excitonic near fields and plasmon polaritons. In this way, it is possible to detect and characterize the spin-forbidden optical transitions of the dark excitons of WSe 2 and molybdenum diselenide (MoSe 2 ) in the far field.…”

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confidence: 99%

Room‐Temperature Low‐Voltage Control of Excitonic Emission in Transition Metal Dichalcogenide Monolayers

Морозов

Wolff

Mortensen

2021

Advanced Optical Materials

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Charge doping of materials with 2D and 3D quantum confinement is a flexible tool to tailor their excitonic emission. Here, using electron doping experiments on transition metal dichalcogenide (TMD) monolayers, reversible tuning of charged exciton emission within a redshift of up to 75 meV is demonstrated by applying very modest voltages (corresponding roughly to the band gap of TMDs), while also controlling the radiative lifetime and intensity. It is found that the neutral exciton ionization dynamics at increasing electron doping follows the Fermi–Dirac distribution, which allows to determine the size of the band gap as well as to extract experimental values for effective masses of electrons and holes at room temperature. The tunable excitonic emission, preserving coherence at room temperature, holds great promise for quantum technologies requiring deterministic coupling with integrated photonic and plasmonic devices.

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“…32 The inter-layer A (1) 1s exciton noted above is momentum-direct with Q = 0, 12, [33][34][35][36] which is distinct from the indirect inter-layer exciton. 37,38 Due to the difference in spin splitting of the bright and the dark states in Mo and W-based TMDCs, the inter-layer exciton is energetically above the intra-layer exciton in MoTe 2 , 33 MoSe 2 , 34 and MoS 2 , 35,36,39 while it is below the intra-layer…”

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Highly Tunable Layered Exciton in Bilayer WS₂: Linear Quantum Confined Stark Effect versus Electrostatic Doping

et al. 2020

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In 1H monolayer transition metal dichalcogenide, the inversion symmetry is broken, while the reflection symmetry is maintained. On the contrary, in the bilayer, the inversion symmetry is restored, but the reflection symmetry is broken. As a consequence of these contrasting symmetries, here we show that bilayer WS 2 exhibits a quantum confined Stark effect (QCSE) that is linear with the applied out-of-plane electric field, in contrary to a quadratic one for a monolayer. The interplay between the unique layer degree of freedom in the bilayer and the field driven partial 1 arXiv:2011.06790v1 [cond-mat.mes-hall] 13 Nov 2020 inter-conversion between intra-layer and inter-layer excitons generates a giant tunability of the exciton oscillator strength. This makes bilayer WS 2 a promising candidate for an atomically thin, tunable electro-absorption modulator at the exciton resonance, particularly when stacked on top of a graphene layer that provides an ultra-fast non-radiative relaxation channel. By tweaking the biasing configuration, we further show that the excitonic response can be largely tuned through electrostatic doping, by efficiently transferring the oscillator strength from neutral to charged exciton. The findings are prospective towards highly tunable, atomically thin, compact and light, on chip, reconfigurable components for next generation optoelectronics.

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Giant Stark splitting of an exciton in bilayer MoS2

Cited by 110 publications

References 36 publications

Interlayer exciton mediated second harmonic generation in bilayer MoS2

Interlayer exciton mediated second harmonic generation in bilayer MoS2

Room‐Temperature Low‐Voltage Control of Excitonic Emission in Transition Metal Dichalcogenide Monolayers

Highly Tunable Layered Exciton in Bilayer WS₂: Linear Quantum Confined Stark Effect versus Electrostatic Doping

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Giant Stark splitting of an exciton in bilayer MoS2

Cited by 110 publications

References 36 publications

Interlayer exciton mediated second harmonic generation in bilayer MoS2

Interlayer exciton mediated second harmonic generation in bilayer MoS2

Room‐Temperature Low‐Voltage Control of Excitonic Emission in Transition Metal Dichalcogenide Monolayers

Highly Tunable Layered Exciton in Bilayer WS2: Linear Quantum Confined Stark Effect versus Electrostatic Doping

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Highly Tunable Layered Exciton in Bilayer WS₂: Linear Quantum Confined Stark Effect versus Electrostatic Doping