scholarly journals Polariton hyperspectral imaging of two-dimensional semiconductor crystals

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Christian Gebhardt ◽  
Michael Förg ◽  
Hisato Yamaguchi ◽  
Ismail Bilgin ◽  
Aditya D. Mohite ◽  
...  
Keyword(s):  
Hyperspectral Imaging ◽  
Transition Metal Dichalcogenides ◽  
Binding Energies ◽  
Strong Coupling Regime ◽  
Two Dimensional ◽  
Strong Light ◽  
Optical Cavities ◽  
Metal Dichalcogenides ◽  
High Level ◽  
Micro Cavity

Abstract Atomically thin crystals of transition metal dichalcogenides (TMDs) host excitons with strong binding energies and sizable light-matter interactions. Coupled to optical cavities, monolayer TMDs routinely reach the regime of strong light-matter coupling, where excitons and photons admix coherently to form polaritons up to room temperature. Here, we explore the two-dimensional nature of TMD polaritons with scanning-cavity hyperspectral imaging. We record a spatial map of polariton properties of extended WS2 monolayers coupled to a tunable micro cavity in the strong coupling regime, and correlate it with maps of exciton extinction and fluorescence taken from the same flake with the cavity. We find a high level of homogeneity, and show that polariton splitting variations are correlated with intrinsic exciton properties such as oscillator strength and linewidth. Moreover, we observe a deviation from thermal equilibrium in the resonant polariton population, which we ascribe to non-Markovian polariton-phonon coupling. Our measurements reveal a promisingly consistent polariton landscape, and highlight the importance of phonons for future polaritonic devices.

scholarly journals Modulation of photocarrier relaxation dynamics in two-dimensional semiconductors

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Yuhan Wang ◽  
Zhonghui Nie ◽  
Fengqiu Wang
Keyword(s):  
Electric Fields ◽  
Mechanical Strain ◽  
Transition Metal Dichalcogenides ◽  
Binding Energies ◽  
Two Dimensional ◽  
Coulomb Interactions ◽  
Relaxation Dynamics ◽  
Strong Light ◽  
2D Semiconductors ◽  
Metal Dichalcogenides

AbstractDue to strong Coulomb interactions, two-dimensional (2D) semiconductors can support excitons with large binding energies and complex many-particle states. Their strong light-matter coupling and emerging excitonic phenomena make them potential candidates for next-generation optoelectronic and valleytronic devices. The relaxation dynamics of optically excited states are a key ingredient of excitonic physics and directly impact the quantum efficiency and operating bandwidth of most photonic devices. Here, we summarize recent efforts in probing and modulating the photocarrier relaxation dynamics in 2D semiconductors. We classify these results according to the relaxation pathways or mechanisms they are associated with. The approaches discussed include both tailoring sample properties, such as the defect distribution and band structure, and applying external stimuli such as electric fields and mechanical strain. Particular emphasis is placed on discussing how the unique features of 2D semiconductors, including enhanced Coulomb interactions, sensitivity to the surrounding environment, flexible van der Waals (vdW) heterostructure construction, and non-degenerate valley/spin index of 2D transition metal dichalcogenides (TMDs), manifest themselves during photocarrier relaxation and how they can be manipulated. The extensive physical mechanisms that can be used to modulate photocarrier relaxation dynamics are instrumental for understanding and utilizing excitonic states in 2D semiconductors.

Strong coupling in two-dimensional materials-based nanostructures: a review

2022 ◽  
Author(s):  
Ye Ming Qing ◽  
Yongze Ren ◽  
Dangyuan Lei ◽  
Hui Feng Ma ◽  
Tie Jun Cui
Keyword(s):  
Strong Coupling ◽  
Coupling Effect ◽  
Transition Metal Dichalcogenides ◽  
Hybrid Nanostructures ◽  
Two Dimensional ◽  
Strong Light ◽  
Two Dimensional Materials ◽  
Potential Applications ◽  
Metal Dichalcogenides ◽  
Emission Behavior

Abstract Strong interaction between electromagnetic radiation and matter leads to the formation of hybrid light-matter states, making the absorption and emission behavior different from those of the uncoupled states. Strong coupling effect results in the famous Rabi splitting and the emergence of new polaritonic eigenmodes, exhibiting spectral anticrossing behavior and unique energy-transfer properties. In recent years, there has been a rapidly increasing number of works focusing on strong coupling between nanostructures and two-dimensional materials (2DMs), because of the exceptional properties and applications they demonstrate. Here, we review the significant recent advances and important developments of strong light-matter interactions in 2DMs-based nanostructures. We adopt the coupled oscillator model to describe the strong coupling and give an overview of various hybrid nanostructures to realize this regime, including graphene-based nanostructures, black phosphorus-based nanostructures, transition-metal dichalcogenides-based nanostructures, etc. In addition, we discuss potential applications that can benefit from these effects and conclude our review with a perspective on the future of this rapidly emerging field.

scholarly journals Monolayer MoS2 for nanoscale photonics

Nanophotonics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1557-1577 ◽  
Author(s):  
Xianguang Yang ◽  
Baojun Li
Keyword(s):  
Near Infrared ◽  
Transition Metal Dichalcogenides ◽  
Single Layer ◽  
Band Gaps ◽  
Laser Source ◽  
Two Dimensional ◽  
Strong Light ◽  
Metal Dichalcogenides ◽  
Optoelectronic Applications ◽  
Flexible Photodetector

AbstractTransition metal dichalcogenides are two-dimensional semiconductors with strong in-plane covalent and weak out-of-plane interactions, resulting in exfoliation into monolayers with atomically thin thickness. This creates a new era for the exploration of two-dimensional physics and device applications. Among them, MoS2 is stable in air and easily available from molybdenite, showing tunable band-gaps in the visible and near-infrared waveband and strong light-matter interactions due to the planar exciton confinement effect. In the single-layer limit, monolayer MoS2 exhibits direct band-gaps and bound excitons, which are fundamentally intriguing for achieving the nanophotonic and optoelectronic applications. In this review, we start from the characterization of monolayer MoS2 in our group and understand the exciton modes, then explore thermal excitons and band renormalization in monolayer MoS2. For nanophotonic applications, the recent progress of nanoscale laser source, exciton-plasmon coupling, photoluminescence manipulation, and the MoS2 integration with nanowires or metasurfaces are overviewed. Because of the benefits brought by the unique electronic and mechanical properties, we also introduce the state of the art of the optoelectronic applications, including photoelectric memory, excitonic transistor, flexible photodetector, and solar cell. The critical applications focused on in this review indicate that MoS2 is a promising material for nanophotonics and optoelectronics.

scholarly journals Strong light-matter coupling in topological metasurfaces integrated with transition metal dichalcogenides

2021 ◽  
Vol 2015 (1) ◽  
pp. 012142
Author(s):  
Ivan Sinev ◽  
Mengyao Li ◽  
Fedor Benimetskiy ◽  
Tatiana Ivanova ◽  
Svetlana Kiriushechkina ◽  
...  
Keyword(s):  
Transition Metal ◽  
Topological Charge ◽  
Transition Metal Dichalcogenides ◽  
Strong Coupling Regime ◽  
Strong Light ◽  
Matter Coupling ◽  
Spin Polarized ◽  
Exciton Polaritons ◽  
Metal Dichalcogenides ◽  
Quantum Phenomena

Abstract Strong light-matter interactions enable unique nonlinear and quantum phenomena at moderate light intensities. Within the last years, polaritonic metasurfaces emerged as a viable candidate for realization of such regimes. In particular, planar photonic structures integrated with 2D excitonic materials, such as transition metal dichalcogenides (TMD), can support exciton polaritons – half-light half-matter quasiparticles. Here, we explore topological exciton polaritons which are formed in a suitably engineered all-dielectric topological photonic metasurface coupled to TMD monolayers. We experimentally demonstrate the transition of topological charge from photonic to polaritonic bands with the onset of strong coupling regime and confirm the presence of one-way spin-polarized edge topological polaritons. The proposed system constitutes a promising platform for photonic/solid-state interfaces for valleytronics and spintronics.

scholarly journals Dynamic polaronic screening for anomalous exciton spin relaxation in two-dimensional lead halide perovskites

2020 ◽  
Vol 6 (47) ◽  
pp. eabb7132
Author(s):  
Weijian Tao ◽  
Qiaohui Zhou ◽  
Haiming Zhu
Keyword(s):  
Spin Dynamics ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Coulomb Interactions ◽  
Strong Light ◽  
Exciton Interaction ◽  
Metal Dichalcogenides ◽  
Excitonic Interactions ◽  
Halide Perovskites ◽  
Lead Halide

Two-dimensional lead halide perovskites with confined excitons have shown exciting potentials in optoelectronic applications. It is intriguing but unclear how the soft and polar lattice redefines excitons in layered perovskites. Here, we reveal the intrinsic exciton properties by investigating exciton spin dynamics, which provides a sensitive probe to exciton coulomb interactions. Compared to transition metal dichalcogenides with comparable exciton binding energy, we observe orders of magnitude smaller exciton-exciton interaction and, counterintuitively, longer exciton spin lifetime at higher temperature. The anomalous spin dynamics implies that excitons exist as exciton polarons with substantially weakened inter- and intra-excitonic interactions by dynamic polaronic screening. The combination of strong light matter interaction from reduced dielectric screening and weakened inter-/intra-exciton interaction from dynamic polaronic screening explains their exceptional performance and provides new rules for quantum-confined optoelectronic and spintronic systems.

scholarly journals Super-resolved Optical Mapping of Reactive Sulfur-Vacancies in Two-Dimensional Transition Metal Dichalcogenides

ACS Nano ◽  
2021 ◽  
Author(s):  
Miao Zhang ◽  
Martina Lihter ◽  
Tzu-Heng Chen ◽  
Michal Macha ◽  
Archith Rayabharam ◽  
...  
Keyword(s):  
Transition Metal ◽  
Optical Mapping ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides

scholarly journals The influence of Coulomb interaction screening on the excitons in disordered two-dimensional insulators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. V. Kirichenko ◽  
V. A. Stephanovich
Keyword(s):  
Coulomb Interaction ◽  
Energy Levels ◽  
Transition Metal Dichalcogenides ◽  
Extreme Case ◽  
Bound State ◽  
Joint Effect ◽  
Two Dimensional ◽  
Inorganic Substances ◽  
Metal Dichalcogenides ◽  
Interaction Screening

AbstractWe study the joint effect of disorder and Coulomb interaction screening on the exciton spectra in two-dimensional (2D) structures. These can be van der Waals structures or heterostructures of organic (polymeric) semiconductors as well as inorganic substances like transition metal dichalcogenides. We consider 2D screened hydrogenic problem with Rytova–Keldysh interaction by means of so-called fractional Scrödinger equation. Our main finding is that above synergy between screening and disorder either destroys the exciton (strong screening) or promote the creation of a bound state, leading to its collapse in the extreme case. Our second finding is energy levels crossing, i.e. the degeneracy (with respect to index $$\mu $$ μ ) of the exciton eigenenergies at certain discrete value of screening radius. Latter effects may also be related to the quantum manifestations of chaotic exciton behavior in above 2D semiconductor structures. Hence, they should be considered in device applications, where the interplay between dielectric screening and disorder is important.

Combined Healing and Doping of Transition Metal Dichalcogenides Through Molecular Functionalization

2021 ◽  
Author(s):  
Sai Manoj Gali ◽  
David Beljonne
Keyword(s):  
Transition Metal ◽  
Charge Transport ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides

Transition Metal Dichalcogenides (TMDCs) are emerging as promising two-dimensional (2D) materials. Yet, TMDCs are prone to inherent defects such as chalcogen vacancies, which are detrimental to charge transport. Passivation of...

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