Evolution of inter-layer coupling in artificially stacked bilayer MoS<sub>2</sub>

Sarkar, Suman; Pradeepa, H L; Nayak, Goutham; Marty, Laëtitia; Renard, Julien; Coraux, Johann; Bendiab, Nedjma; Bouchiat, Vincent; Basu, J. K.; Bid, Aveek

doi:10.1039/c9na00517j

Cited by 10 publications

(7 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, the spectral shape of each exciton resonance is asymmetric with low-energy tailing due to the trion states, rendering the spectral width significantly broader than that of the decoupled BL, which is basically the same as the ML case (black trace). The broader SHG profile (pink symbols) from the weakly coupled BL is also consistent with the corresponding Δ R and indicates that SHG can be enhanced at the trion states; we believe that this trion state might be accidentally caused by the ML transfer/stacking process . Although it was not possible to precisely locate the A - and B -exciton resonances in the weakly coupled BL because of the trion states, we believe that they are rather similar to those in the as-grown BL based on the PL data shown in Figure S4c.…”

Section: Resultssupporting

confidence: 73%

“…However, the phase-mismatch issue is still present even with the band modification of the BL induced by nonzero interlayer coupling, which will be discussed later. In order to investigate the effect of enhanced coupling, we annealed the weakly coupled BLs at 350 °C for 1 h in the presence of mixed gases Ar/H 2 , which removes an air gap between the MLs to recover ideal vdW structures. , In Figure b we plot the broadband SHG responses of annealed BLs at x = 0 (black), 0.3 (blue), and 0.45 (green). Interestingly, the measured SHG profiles are clearly different from those from the specimens before annealing.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS₂/MoS_2(1–x)Se_2x Structures

Kim

Ullah

et al. 2020

ACS Nano

View full text Add to dashboard Cite

Noncentrosymmetric monolayers (MLs) of transition metal dichalcogenides (TMDCs) and their 3R-type vertical stacks provide an ideal platform for studying atomic-scale nonlinear light− matter interaction in terms of second harmonic generation (SHG). Unlike the case of MLs, SHG from artificial stacks can be nontrivially affected by interlayer coupling and band offset between the constituent MLs, where the latter occurs for band-gap-engineered vertical heterostructures (VHs). In order to study these effects, we produced different sets of 3R-type homobilayers (homo-BLs) and heterobilayers (hetero-BLs) composed of MoS 2 and its ternary alloy MoS 2(1−x) Se 2x . We first investigated the impact of interlayer coupling on the SHG response across the Aand B-exciton resonances in the MoS 2 homo-BLs. The coupling strength was varied by preparing (i) decoupled BLs (SiO 2 intercalated), (ii) weakly coupled BLs (dry transferred), and (iii) strongly coupled BLs (postannealed) and monitored by photoluminescence, Raman, and reflectance difference spectroscopy, and atomic force microscopy. Unlike the decoupled BL, SHG in the coupled BLs cannot be explained by the simple square law in thickness due to coupling-induced band modification. The impact of exciton-resonance offset on SHG was also investigated in the hetero-BLs by controlling the Se concentration in MoS 2x Se 2(x−1) . Although these VHs can significantly broaden the spectral range for efficient SHG by vertically superposing distinct resonances of the constituent MLs, coherent reinforcement of SHG cannot be achieved basically because of the π/2 phase difference between the on-resonance SHG field in one ML and the off-resonance SHG field in the other ML. Upon postannealing, however, the overlapping resonance regime exhibited unexpectedly high SHG enhancement. This may arise from the formation of the strong resonance when the VHs approach ideal 3R-type hetero-BLs. Our approach may be utilized for fully exploiting the TMDC VHs for highly efficient broadband SHG applications.

show abstract

Section: Resultssupporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS₂/MoS_2(1–x)Se_2x Structures

Kim

Ullah

et al. 2020

ACS Nano

View full text Add to dashboard Cite

show abstract

“…The monolayer is transferred on to HMM by dry visco-elastic gel stamping. 36,37 Further details are provided in supporting material.…”

Section: Coupling Strength Calculationsmentioning

confidence: 99%

Selectively strong coupling MoS$_2$ excitons to a metamaterial at room temperature

Kalluru,

Basu

2022

Preprint

Self Cite

View full text Add to dashboard Cite

Light emitters in vicinity of a hyperbolic metamaterial (HMM) show a range of quantum optical phenomena from spontaneous decay rate enhancement to strong coupling. In this study, we integrate monolayer Molybdenum disulfide (MoS 2 ) emitter in near field region of HMM. The MoS 2 monolayer has A and B excitons, which emit in the red region of visible spectrum. We find that the B excitons couple to HMM differently compared to A excitons. The fabricated HMM transforms to a hyperbolic dispersive medium at ≃ 2.13 eV, from an elliptical dispersive medium. The selective coupling of B Excitons to the HMM modes is attributed to the inbuilt field gradient of the transition. The B exciton energy lies close to the transition point of the HMM, relative to A Exciton. So, the HMM modes couple more to the B excitons and the metamaterial functions as selective coupler. The coupling strength calculations show that coupling is 2.5 times stronger for B excitons relative to A excitons. High near field of HMM, large magnitude and the in-plane transition dipole moment of MoS 2 Excitons, result in strong coupling of B excitons and formation of hybrid light-matter states. The measured differential Reflection and Photoluminescence spectra indicate the presence of hybrid light-matter states i.e. Exciton-Polaritons. Rabi splitting of

show abstract

“…Finally, an hBN flake of thickness ∼30 nm was transferred to the device to avoid environmental degradation of the heterostructure. As a final step, the device was vacuum annealed at 200 • C to improve the coupling between the MoS 2 and NbSe 2 layers [36].…”

Section: Appendix B: Details Of Device Fabricationmentioning

confidence: 99%

Transition from three- to two-dimensional Ising superconductivity in few-layer NbSe2 by proximity effect from van der Waals heterostacking

et al. 2021

Self Cite

View full text Add to dashboard Cite

We report the experimental observation of Ising superconductivity in three-dimensional NbSe 2 stacked with single-layer MoS 2 . The angular dependence of the upper critical magnetic field and the temperature dependence of the upper parallel critical field confirm the appearance of two-dimensional Ising superconductivity in threedimensional NbSe 2 with a single-layer MoS 2 overlay. We show that the superconducting phase has strong Ising spin-orbit correlations which make the holes spin nondegenerate. Our observation of Ising superconductivity in heterostructures of few-layer NbSe 2 of thickness ∼15 nm with single-layer MoS 2 raises the interesting prospect of observing topological chiral superconductors with nontrivial Chern numbers in a momentum-space spin-split fermionic system.

show abstract

Evolution of inter-layer coupling in artificially stacked bilayer MoS₂

Cited by 10 publications

References 60 publications

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS₂/MoS_2(1–x)Se_2x Structures

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS₂/MoS_2(1–x)Se_2x Structures

Selectively strong coupling MoS$_2$ excitons to a metamaterial at room temperature

Transition from three- to two-dimensional Ising superconductivity in few-layer NbSe2 by proximity effect from van der Waals heterostacking

Contact Info

Product

Resources

About

Evolution of inter-layer coupling in artificially stacked bilayer MoS2

Cited by 10 publications

References 60 publications

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS2/MoS2(1–x)Se2x Structures

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS2/MoS2(1–x)Se2x Structures

Selectively strong coupling MoS$_2$ excitons to a metamaterial at room temperature

Transition from three- to two-dimensional Ising superconductivity in few-layer NbSe2 by proximity effect from van der Waals heterostacking

Contact Info

Product

Resources

About

Evolution of inter-layer coupling in artificially stacked bilayer MoS₂

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS₂/MoS_2(1–x)Se_2x Structures

Effects of Interlayer Coupling and Band Offset on Second Harmonic Generation in Vertical MoS₂/MoS_2(1–x)Se_2x Structures