Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides

Selig, Malte; Berghäuser, Gunnar; Raja, Archana; Nagler, Philipp; Schüller, Christian; Heinz, Tony F.; Korn, Tobias; Chernikov, Alexey; Malić, Ermin; Knorr, Andreas

doi:10.1117/12.2252486

Cited by 80 publications

(162 citation statements)

References 46 publications

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“…In this review, we highlight the distinctive characteristics of the QD-phonon interaction which differs significantly from carrier-phonon interactions in extended semiconductors. In fact, in bulk materials or in two-dimensional semiconductors, like the recently found monolayers of transition metal dichalcogenides [7,8], there are usually many possibilities to reach another electric state from a given initial state by a phonon emission or absorption process that respects the conservation of energy and momentum on the single particle level. However, phonon energies do typically not match the discrete electronic transition energies in QDs.…”

Section: Introductionmentioning

confidence: 99%

Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

Reiter

Kuhn

Axt

2019

Advances in Physics: X

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We review distinct features arising from the unique nature of the carrier-phonon coupling in self-assembled semiconductor quantum dots. Because of the discrete electronic energy structure, the pure dephasing coupling usually dominates the phonon effects, of which two properties are of key importance: The resonant nature of the dot-phonon coupling, i.e. its nonmonotonic behavior as a function of energy, and the fact that it is of super-Ohmic type. Phonons do not only act destructively in quantum dots by introducing dephasing, they also offer new opportunities, e.g. in state preparation protocols. Apart from being an interesting model systems for studying fundamental physical aspects, quantum dot and quantum dot-microcavity systems are a hotspot for many innovative applications. We discuss recent developments related to the decisive impact of phonons on key figures of merit of photonic devices like single or entangled photon sources under aspects like indistinguishability, purity and brightness. All in all it follows that understanding and controlling the carrier-phonon interaction in semiconductor quantum dots is vital for their usage in quantum information technology.

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Section: Introductionmentioning

confidence: 99%

Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

Reiter

Kuhn

Axt

2019

Advances in Physics: X

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“…The strength of the interactions between coupled charge carriers and phonons is deduced from experimental measurements of the dephasing times [55], exciton linewidths [56], photoluminescence, [57] and other parameters such as the exciton mobility and luminescence rise times. The exciton formation time is determined by a complicated interplay of various dynamical processes in the picosecond time scale [58] and is linked to the efficient operation of optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Exciton formation assisted by longitudinal optical phonons in monolayer transition metal dichalcogenides

Thilagam

2016

Journal of Applied Physics

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We examine a mechanism by which excitons are generated via the LO (longitudinal optical) phonon-assisted scattering process after optical excitation of monolayer transition metal dichalcogenides. The exciton formation time is computed as a function of the exciton center-of-mass wavevector, electron and hole temperatures, and carrier densities for known values of the Fröhlich coupling constant, LO phonon energy, lattice temperature, and the exciton binding energy in layered structures. For the monolayer MoS2, we obtain ultrafast exciton formation times on the sub-picosecond time scale at charge densities of 5 × 10 11 cm −2 and carrier temperatures less than 300 K, in good agreement with recent experimental findings (≈ 0.3 ps). While excitons are dominantly created at zero center-of-mass wavevectors at low charge carrier temperatures (≈ 30 K), the exciton formation time is most rapid at non-zero wavevectors at higher temperatures (≥ 120 K) of charge carriers. The results show the inverse square-law dependence of the exciton formation times on the carrier density, consistent with a squarelaw dependence of photoluminescence on the excitation density. Our results show that excitons are formed more rapidly in exemplary monolayer selenide-based dichalcogenides (MoSe2 and WSe2) than sulphide-based dichalcogenides (MoS2 and WS2).

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“…Exciton-phonon coupling (EXPC) plays a key role in determining the T-dependent optoelectronic and transport properties of 1L-TMDs [9][10][11] . It is responsible for, e.g., nonradiative exciton decay 9,10,12 , limiting the fluorescence quantum yield 13 , the formation of darkexciton phonon replicas 14 , and it mediates spin-flip processes, thus decreasing the lifetime of spin/valley-polarized charge carriers 15 . For T<100 K, the interaction between excitons and acoustic phonons induces linewidth broadening and dominates the excitonic resonance of 1L-TMDs 9,16,17 .…”

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confidence: 99%

Exciton–phonon coupling strength in single-layer MoSe2 at room temperature

Trovatello

Conte

et al. 2020

Preprint

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Single-layer transition metal dichalcogenides (1L-TMDs) are at the center of an ever increasing research effort both in terms of fundamental physics and applications. Exciton–phonon coupling (EXPC) plays a key role in determining the photonic and (opto)electronic properties of 1L-TMDs. However, the EXPC strength has not been measured at room temperature. Here, we develop two-dimensional (2D) micro-spectroscopy to determine EXPC of 1L-MoSe2. We detect beating signals as a function of waiting time T, induced by the coupling between the A exciton and the A'1 optical phonon. Analysis of 2D beating maps provides the EXPC with the help of simulations. The Huang–Rhys factor of ~1 is larger than in most other inorganic semiconductor nanostructures. Our technique offers a unique tool to measure EXPC also in other 1L-TMDs and heterogeneous semiconducting systems with a spatial resolution ~260 nm, and will provide design-relevant parameters for the development of novel optoelectronic devices.

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Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides

Cited by 80 publications

References 46 publications

Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

Exciton formation assisted by longitudinal optical phonons in monolayer transition metal dichalcogenides

Exciton–phonon coupling strength in single-layer MoSe2 at room temperature

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