Substrate engineering for high-quality emission of free and localized excitons from atomic monolayers in hybrid architectures

Iff, Oliver; He, Yuming; Lundt, Nils; Stoll, S.; Baumann, Vasilij; Höfling, Sven; Schneider, Christian

doi:10.1364/optica.4.000669

Cited by 29 publications

(24 citation statements)

References 25 publications

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“…This can be prominently seen in the LIX 1 peak, which jitters by up to~1 meV between measurements. Similar spectral wandering has also been reported from discrete emitters in monolayer WSe 2 , where it is commonly attributed to timedependent fluctuations in the local electrostatic environment 39,40 . The mid-point of the biexciton LIX 2 doublet is significantly blueshifted by (8.4 ± 0.6) meV with respect to LIX 1 and the two components are separated by~(1.2 ± 0.5) meV.…”

Section: Spectroscopy Of Trapped Few-exciton Statessupporting

confidence: 77%

Discrete interactions between a few interlayer excitons trapped at a MoSe2–WSe2 heterointerface

et al. 2020

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Inter-layer excitons (IXs) in hetero-bilayers of transition metal dichalcogenides (TMDs) represent an exciting emergent class of long-lived dipolar composite bosons in an atomically thin, near-ideal two-dimensional (2D) system. The long-range interactions that arise from the spatial separation of electrons and holes can give rise to novel quantum, as well as classical multi-particle correlation effects. Indeed, first indications of exciton condensation have been reported recently. In order to acquire a detailed understanding of the possible many-body effects, the fundamental interactions between individual IXs have to be studied. Here, we trap a tunable number of dipolar IXs (NIX ~ 1–5) within a nanoscale confinement potential induced by placing a MoSe2–WSe2 hetero-bilayer (HBL) onto an array of SiO2 nanopillars. We control the mean occupation of the IX trap via the optical excitation level and observe discrete sharp-line emission from different configurations of interacting IXs. The intensities of these features exhibit characteristic near linear, quadratic, cubic, quartic and quintic power dependencies, which allows us to identify them as different multiparticle configurations with NIX ~ 1–5. We directly measure the hierarchy of dipolar and exchange interactions as NIX increases. The interlayer biexciton (NIX = 2) is found to be an emission doublet that is blue-shifted from the single exciton by ΔE = (8.4 ± 0.6) meV and split by 2J = (1.2 ± 0.5) meV. The blueshift is even more pronounced for triexcitons ((12.4 ± 0.4) meV), quadexcitons ((15.5 ± 0.6) meV) and quintexcitons ((18.2 ± 0.8) meV). These values are shown to be mutually consistent with numerical modelling of dipolar excitons confined to a harmonic trapping potential having a confinement lengthscale in the range $$\ell \approx 3$$ ℓ ≈ 3 nm. Our results contribute to the understanding of interactions between IXs in TMD hetero-bilayers at the discrete limit of only a few excitations and represent a key step towards exploring quantum correlations between IXs in TMD hetero-bilayers.

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Section: Spectroscopy Of Trapped Few-exciton Statessupporting

confidence: 77%

Discrete interactions between a few interlayer excitons trapped at a MoSe2–WSe2 heterointerface

et al. 2020

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“…Even in quantum emitters hosted by insulating 2D materials such as hBN, a photon coherence time of 81 ps was measured, which is less than the lifetime limited value due to the ultrafast spectral wandering in these emitters [32]. However, using different substrates such as Al 2 O 3 [33] or GaInP [34,35] has improved the quality and reduced the random spectral fluctuations of quantum emitters in both insulating [~45 μeV full width at half-maximum (FWHM) with nonresonant excitation] and semiconducting (70 μeV FWHM with nonresonant excitation) 2D materials. While resonant excitation was used to stabilize the ZPL for few tens of seconds [36], anti-Stokes excitation of quantum emitters in hBN was also used to suppress the spectral wandering [37].…”

Section: Quantum Light From 2d Semiconductors and Insulatorsmentioning

confidence: 96%

Advances in quantum light emission from 2D materials

2019

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Two-dimensional (2D) materials are being actively researched due to their exotic electronic and optical properties, including a layer-dependent bandgap, a strong exciton binding energy, and a direct optical access to electron valley index in momentum space. Recently, it was discovered that 2D materials with bandgaps could host quantum emitters with exceptional brightness, spectral tunability, and, in some cases, also spin properties. This review considers the recent progress in the experimental and theoretical understanding of these localized defect-like emitters in a variety of 2D materials as well as the future advantages and challenges on the path toward practical applications.

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“…The tube surface remains clear after manipulations, without any contaminations. Importantly, the use of free‐standing samples excluded the possible effect of a substrate . Besides, it permitted us to perform the TEM characterization of selected tubes to obtain information on their structural properties.…”

Section: Experimental Details and Samples Characterizationmentioning

confidence: 99%

Excitonic Emission in van der Waals Nanotubes of Transition Metal Dichalcogenides

et al. 2019

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Nanotubes (NTs) of transition metal dichalcogenides (TMDs), were first synthesized more than a quarter of a century ago; nevertheless, many of their optical properties have so far remained basically unknown. Herein, the state of the art in the knowledge of the optical properties of TMD NTs is presented. First, general properties of multilayered crystals are evaluated, and available data on related NTs are analyzed. Then, the technology for the formation and the structural characteristics of NTs are represented, focusing on the structures synthesized by chemical transport reaction. The core of this work is the presentation of the ability of synthesized TMD NTs to emit bright photoluminescence (PL), which has been discovered recently. By means of micro-PL spectroscopy of individual tubes, we show that excitonic transitions relevant to both direct and indirect band gaps contribute to the emission spectra of the NTs despite having the dozens of monolayers in their walls. The performance of the tubes as efficient optical resonators is highlighted, where confined optical modes strongly affect the emission. Finally, a brief conclusion is presented, along with an outlook of the future studies of this novel radiative member of the NTs family, which have unique potential for different nanophotonics applications.

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Substrate engineering for high-quality emission of free and localized excitons from atomic monolayers in hybrid architectures

Cited by 29 publications

References 25 publications

Discrete interactions between a few interlayer excitons trapped at a MoSe2–WSe2 heterointerface

Discrete interactions between a few interlayer excitons trapped at a MoSe2–WSe2 heterointerface

Advances in quantum light emission from 2D materials

Excitonic Emission in van der Waals Nanotubes of Transition Metal Dichalcogenides

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