Dielectric Nanoantennas for Strain Engineering in Atomically Thin Two-Dimensional Semiconductors

Sortino, Luca; Brooks, Matthew; Zotev, Panaiot G.; Genco, Armando; Cambiasso, Javier; Mignuzzi, Sandro; Maier, Stefan A.; Burkard, Guido; Sapienza, Riccardo; Tartakovskii, A. I.

doi:10.1021/acsphotonics.0c00294

Cited by 32 publications

(40 citation statements)

References 70 publications

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“…Despite these promising first results, the physical mechanisms that govern changes in the TMD emission as they are placed in proximity of the nanoresonators need to be understood. In addition to the targeted modification of the local electric field due to the resonator, several other mechanisms such as strong local strain induced by the resonator [22] and changing optical dipole orientation with respect to the detection contribute to brightening and change in directivity of the emission.…”

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confidence: 99%

Unveiling the Optical Emission Channels of Monolayer Semiconductors Coupled to Silicon Nanoantennas

et al. 2020

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Monolayers (MLs) of transition metal dichalcogenides (TMDs) such as WSe2 and MoSe2 can be placed by dry stamping directly on broadband dielectric resonators, which have the ability to enhance the spontaneous emission rate and brightness of solid-state emitters at room temperature. We show strongly enhanced emission and directivity modifications in room-temperature photoluminescence mapping experiments. By varying TMD material (WSe2 vs MoSe2) transferred on silicon nanoresonators with various designs (planarized vs nonplanarized), we experimentally separate the different physical mechanisms that govern the global light emission enhancement. For WSe2 and MoSe2, we address the effects of Mie resonances and strain in the monolayer. For WSe2, an important additional contribution comes from out-of-plane exciton dipoles. This paves the way for more targeted designs of TMD-Si nanoresonator structures for room-temperature applications.

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confidence: 99%

Unveiling the Optical Emission Channels of Monolayer Semiconductors Coupled to Silicon Nanoantennas

et al. 2020

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“…Contrary to other group-VI TMDs, tensile strain in WSe 2 results in the lowering of the conduction band (CB) minimum and the rise of the valence band (VB) maximum, as shown in Fig. 3a, both located at the K points in the momentum space 8,35 . This creates an energy landscape where a very small fraction of the 2D exciton population may be captured into such 0D centers, giving rise to nonclassical light emission from confined states, at photon energies lower than that of both bright and dark excitons in unstrained WSe 2 .…”

Section: Resultsmentioning

confidence: 90%

“…1f. In what follows, we focus on GaP dimer nanoantennas, as these provide pronounced and interesting photonic effects, as was shown in our preliminary work 7,8 . On the other hand, less studied GaP monomers (single nanopillars) may also be useful for achieving SPE positioning and improved PL in WSe 2 monolayers.…”

Section: Resultsmentioning

confidence: 99%

“…ingle-photon emitters (SPEs) in two-dimensional (2D) semiconducting WSe 2 [1][2][3][4][5] open attractive perspectives for few-atom-thick devices for quantum technologies owing to favorable excitonic properties 6 and the integration with arbitrary substrates, including nanostructured surfaces 7,8 . Several theoretical models have been proposed to provide insight into the origin of SPEs observed in the cryogenic photoluminescence (PL) spectra of 2D WSe 2 [9][10][11][12] .…”

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confidence: 99%

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Bright single photon emitters with enhanced quantum efficiency in a two-dimensional semiconductor coupled with dielectric nano-antennas

et al. 2021

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Single photon emitters in atomically-thin semiconductors can be deterministically positioned using strain induced by underlying nano-structures. Here, we couple monolayer WSe2 to high-refractive-index gallium phosphide dielectric nano-antennas providing both optical enhancement and monolayer deformation. For single photon emitters formed on such nano-antennas, we find very low (femto-Joule) saturation pulse energies and up to 104 times brighter photoluminescence than in WSe2 placed on low-refractive-index SiO2 pillars. We show that the key to these observations is the increase on average by a factor of 5 of the quantum efficiency of the emitters coupled to the nano-antennas. This further allows us to gain new insights into their photoluminescence dynamics, revealing the roles of the dark exciton reservoir and Auger processes. We also find that the coherence time of such emitters is limited by intrinsic dephasing processes. Our work establishes dielectric nano-antennas as a platform for high-efficiency quantum light generation in monolayer semiconductors.

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“…The latter being independent of the Au NPs optical density, the absorption of the MoSe 2 PL emission by the Au NPs can be ruled out to account for the observed PL quenching of MoSe 2 . Several studies [16,[36][37][38][39][40][41][42][43][44] showed that the strain imposed by the metal NPs to the TMD layer may strongly modify its electronic band structure and can be responsible for a strong quenching of the PL emission. In particular, tensile strain may induce a direct-to-indirect band gap transition [37,41,42] which leads to a red shift of the PL peak and to a drastic decrease of the PL intensity [38,39,42,43].…”

Section: Resultsmentioning

confidence: 99%

Plasmon damping and charge transfer pathways in Au@MoSe2 nanostructures

Abid

Benzo

Pécassou

et al. 2021

Materials Today Nano

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Hybridization of plasmonic and excitonic elementary excitations provides an efficient mean of enhancing the optical absorption and emission properties of metal/semiconductor nanostructures and is a key concept for the design of novel efficient optoelectronic devices.Here we investigate the optical properties of 2D MoSe 2 quantum well flakes covered with Au nanoparticles supporting plasmonic resonances. Using spatially resolved confocal spectroscopy, we report the observation of a quenching phenomenon of the Raman scattering and photoluminescence emission of both the MoSe 2 layer and the Au nanoparticles. We found that the quenching of the photoluminescence emission from the Au nanoparticles is partial and measurable unlike the one observed for the Au-covered MoSe 2 layers, which is total. Its dependence on the thickness of the MoSe 2 layer is determined experimentally. Based on electro-dynamics calculations and on the electronic band alignment at the Au/ MoSe 2 interface, the results are interpreted in terms of i) damping of the plasmonic resonance of the Au nanoparticles due to the optical absorption by the MoSe 2 layer ii) a two-pathways charge transfer scheme where the photo-excited electrons leak from the MoSe 2 layer to the Au NPs whereas the photo-excited holes flow in the opposite direction i.e., from the Au NPs to the MoSe 2 layer. The two combined mechanisms account well for the experimental observations and complements the interpretations proposed in the literature for similar metal nanoparticles/transition metal dichalcogenide systems.

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Dielectric Nanoantennas for Strain Engineering in Atomically Thin Two-Dimensional Semiconductors

Cited by 32 publications

References 70 publications

Unveiling the Optical Emission Channels of Monolayer Semiconductors Coupled to Silicon Nanoantennas

Unveiling the Optical Emission Channels of Monolayer Semiconductors Coupled to Silicon Nanoantennas

Bright single photon emitters with enhanced quantum efficiency in a two-dimensional semiconductor coupled with dielectric nano-antennas

Plasmon damping and charge transfer pathways in Au@MoSe2 nanostructures

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