Discrete quantum dot like emitters in monolayer MoSe2: Spatial mapping, magneto-optics, and charge tuning

Branny, Artur; Wang, G; Kumar, Santosh; Robert, Cédric; Lassagne, B.; Marie, X.; Gerardot, Brian D.; Urbaszek, B.

doi:10.1063/1.4945268

Cited by 115 publications

(123 citation statements)

References 53 publications

(126 reference statements)

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“…As a general trend observed in the experimental studies, biaxial strain induces a significantly stronger modulation when compared to uniaxial strain, a fact also supported by ab-initio calculations [53,54]. Furthermore, by strain engineering it is possible to localize excitons in specific * klaus.zollner@physik.uni-regensburg.de regions, which is a viable approach to obtain spatially and spectrally isolated quantum emitters based on 2D materials [51,[55][56][57][58].…”

Section: Introductionsupporting

confidence: 59%

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

2019

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When considering transition-metal dichalcogenides (TMDCs) in van der Waals (vdW) heterostructures for periodic ab-initio calculations, usually, lattice mismatch is present, and the TMDC needs to be strained. In this study we provide a systematic assessment of biaxial strain effects on the orbital, spin-orbit, and optical properties of the monolayer TMDCs using ab-initio calculations. We complement our analysis with a minimal tight-binding Hamiltonian that captures the low-energy bands of the TMDCs around K and K' valleys. We find characteristic trends of the orbital and spinorbit parameters as a function of the biaxial strain. Specifically, the orbital gap decreases linearly, while the valence (conduction) band spin splitting increases (decreases) nonlinearly in magnitude when the lattice constant increases. Furthermore, employing the Bethe-Salpeter equation and the extracted parameters, we show the evolution of several exciton peaks, with biaxial strain, on different dielectric surroundings, which are particularly useful for interpreting experiments studying strain-tunable optical spectra of TMDCs.

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Section: Introductionsupporting

confidence: 59%

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

2019

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“…Spatially, it was known that the discrete lines occur often at the edges of flakes and the regions of high strain gradient. 2,[9][10][11] We find that for most samples the studied 2D exciton peaks disappear under an applied pressure of ~ 0.6−1.5 GPa at the first cycle of in situ pressure-changing process. After releasing the pressure to zero, a remarkable change of PL lineshape is observed, as typically shown in Fig.…”

Section: (A) 3(c) and 4(b) It Is Verymentioning

confidence: 75%

“…[1][2][3][4][5][6][7][8][9] Local strain gradients which occur at the edges are considered to modulate the electronic states of the localized excitons, 2, 9-11 resulting in spatially and spectrally isolated single photon emission. This means that strain engineering is an effective approach to obtain spatially and spectrally isolated quantum emitters in two-dimensional (2D) semiconductors.…”

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confidence: 99%

Single photon emission from deep-level defects in monolayerWSe2

Dou

Ding

et al. 2017

Phys. Rev. B

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We report an efficient method to observe single photon emissions in monolayer WSe 2 by applying hydrostatic pressure. The photoluminescence peaks of typical two-dimensional (2D) excitons show a nearly identical pressure-induced blue-shift, whereas the energy of pressureinduced discrete emission lines (quantum emitters) demonstrates a pressure insensitive behavior.The decay time of these discrete line emissions is approximately 10 ns, which is at least one order longer than the lifetime of the broad localized (L) excitons. These characteristics lead to a conclusion that the excitons bound to deep level defects can be responsible for the observed single photon emissions.

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“…It is well known, however, that the exciton binding is large in TMDCs and plays a significant role in optical experiments [33,34]. The effects of Coulomb interaction between an electron and a hole as well as localization by an in-plane potential [35] can be estimated by introducing the g-factor dependence on a charge carrier energy. Such a dependence is derived by simply replacing E c with E c + ∆E c in Eq.…”

Section: Discussionmentioning

confidence: 99%

Atomically inspiredk·papproach and valley Zeeman effect in transition metal dichalcogenide monolayers

2017

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We developed a six-band k · p model that describes the electronic states of monolayer transition metal dichalcogenides (TMDCs) in K-valleys. The set of parameters for the k · p model is uniquely determined by decomposing tight-binding (TB) models in the vicinity of K ± -points. First, we used TB models existing in literature to derive systematic parametrizations for different materials, including MoS2, WS2, MoSe2 and WSe2. Then, by using the derived six-band k · p Hamiltonian we calculated effective masses, Landau levels, and the effective exciton g-factor g X 0 in different TMDCs. We showed that TB parameterizations existing in literature result in small absolute values of g X 0 , which are far from the experimentally measured g X 0 ≈ −4. To further investigate this issue we derived two additional sets of k · p parameters by developing our own TB parameterizations based on simultaneous fitting of ab-initio calculated, within the density functional (DFT) and GW approaches, energy dispersion and the value of g X 0 . We showed that the change in TB parameters, which only slightly affects the dispersion of higher conduction and deep valence bands, may result in a significant increase of |g X 0 |, yielding close-to-experiment values of g X 0 . Such a high parameter sensitivity of g X 0 opens a way to further improvement of DFT and TB models.

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Discrete quantum dot like emitters in monolayer MoSe2: Spatial mapping, magneto-optics, and charge tuning

Cited by 115 publications

References 53 publications

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

Single photon emission from deep-level defects in monolayerWSe2

Atomically inspiredk·papproach and valley Zeeman effect in transition metal dichalcogenide monolayers

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