Disorder-dependent valley properties in monolayer 
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Tran, Kha; Singh, Akshay; Seifert, Joe; Wang, Yiping; Hao, Kai; Huang, Jing; Li, Lain‐Jong; Taniguchi, Takashi; Watanabe, Kenji; Li, Xiaoqin

doi:10.1103/physrevb.96.041302

Cited by 19 publications

(19 citation statements)

References 44 publications

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“…The absence of a Stokes shift between the maxima in PL and PLE exclude any effects of localization on the exciton emission, which might arise because of defects or disorder in our (strained) WSe 2 MLs, in contrast to what was reported in Ref. [42]. Moreover, our PLE measurements provide further evidence for the energy level diagram presented in Fig.…”

Section: Methodssupporting

confidence: 79%

Observation of bright exciton splitting in strained WSe2 monolayers

et al. 2018

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High-resolution magnetophotoluminescence measurements of strained WSe 2 monolayers are reported. At low temperature, a splitting of a few meV in the neutral exciton peak is observed, which is attributed to the theoretically predicted in-plane (xy) anisotropy splitting. Measurements in high magnetic fields up to 30 T demonstrate that strain and intervalley electron-hole exchange mix the valley-exciton energy levels, leading to a relaxation of the valley-selective optical selection rules and to strongly modified exciton g factors. Our observation of the bright exciton splitting provides crucial information about the dispersion of valley excitons and paves the way to develop valley functionality for photonic devices.

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Section: Methodssupporting

confidence: 79%

Observation of bright exciton splitting in strained WSe2 monolayers

et al. 2018

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“…[66] The Stokes shift between the luminescence and absorption peaks will result in a shift of the CL peaks compared to EELS spectra. [67] However, this effect has been shown to cause only a minor effect compared to the strong-coupling effects we observe here, for nominally undoped materials, whereas it can be significantly increased for n-doped materials. [68] The short interaction of the electron beam with our structure does not cause any significant sample heating or doping, as the positions of the peaks do not depend on the acquisition time, the acceleration voltage within the range of 5 to 30 keV, and also not on the probe current within the range of 10 to 20 nA (see Figure S6, Supporting Information).…”

Section: Discussioncontrasting

confidence: 51%

Charting the Exciton–Polariton Landscape of WSe₂ Thin Flakes by Cathodoluminescence Spectroscopy

Taleb

Davoodi

Diekmann

et al. 2021

Advanced Photonics Research

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“…Thus, we assume the coincidence between the PL emission peak and the optical bandgap only for temperatures above T ≥ 70 K. Our experimental data for ε PL (T) at T ≥ 70 K can be fitted by Equation ( 14) for all three studied materials. The fitting parameters for the three monolayers are listed in [88,89] Furthermore, systematic studies of Stokes shifts in TMDs based on a comparison between PL emission and optical absorption/transmission data provide results in the range of 4-14 meV, [151][152][153][154][155] which are in agreements with the values for Stokes shifts given in our study by the differences between the fitted E op (0) values and the PL peak positions ε PL (0).…”

Section: Phonon-induced Effectssupporting

confidence: 83%

Energy Scaling of Compositional Disorder in Ternary Transition‐Metal Dichalcogenide Monolayers

Masenda

Schneider

Aly

et al. 2021

Adv Elect Materials

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to play a crucial role as essential building blocks in future high-tech devices. [1][2][3][4][5][6][7][8] Already in the late 1960s, early studies on the structural and electronic properties of bulk TMDs had started and are detailed in a report by Wilson and Yoffe. [9] TMDs are layered materials which combine a transition metal (M: Mo, W, Ti, Zr, etc.) and a chalcogen (X: S, Se, or Te) in the general formula MX 2 with one layer of M atoms sandwiched between two layers of X atoms. [10] Group VIB TMDs with a 2H structural phase (e.g., MoSe 2 ) are the most explored representatives of such systems. They are characterized by an intrinsic bandgap within the visible and near-infrared regions. [11] Furthermore, the material system exhibits a transition from an indirect to a direct bandgap located at the K or K′ points of the hexagonal Brillouin zone, linked to a decrease in the number of layers from the bulk crystal to a monolayer. [12,13] Moreover, such materials also possess a strong spin-orbit interaction due to the presence of a relatively heavy transition metal along with huge exciton binding energies [14][15][16] resulting from a strong Coulomb interaction and a lack of dielectric screening. These properties lead to a valence-band splitting that strongly affects Alloying semiconductors is often used to tune the material properties desired for device applications. The price for this tunability is the extra disorder caused by alloying. In order to reveal the features of the disorder potential in alloys of atomically thin transition-metal dichalcogenides (TMDs) such as Mo x W 1−x Se 2 , the exciton photoluminescence is measured in a broad temperature range between 10 and 200 K. In contrast to the binary materials MoSe 2 and WSe 2 , the ternary system demonstrates non-monotonous temperature dependences of the luminescence Stokes shift and of the luminescence linewidth. Such behavior is a strong indication of a disorder potential that creates localized states for excitons and affects the exciton dynamics responsible for the observed non-monotonous temperature dependences. A comparison between the experimental data and the results obtained by Monte Carlo computer simulations provides information on the energy scale of the disorder potential and also on the shape of the density of localized states created by disorder. Statistical spatial fluctuations in the distribution of the chemically different material constituents are revealed to cause the disorder potential responsible for the observed effects. A deeper understanding of the disorderinduced effects is vital for prospective TMD alloy-based devices.

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Disorder-dependent valley properties in monolayer WSe2

Cited by 19 publications

References 44 publications

Observation of bright exciton splitting in strained WSe2 monolayers

Observation of bright exciton splitting in strained WSe2 monolayers

Charting the Exciton–Polariton Landscape of WSe₂ Thin Flakes by Cathodoluminescence Spectroscopy

Energy Scaling of Compositional Disorder in Ternary Transition‐Metal Dichalcogenide Monolayers

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Disorder-dependent valley properties in monolayer WSe2

Cited by 19 publications

References 44 publications

Observation of bright exciton splitting in strained WSe2 monolayers

Observation of bright exciton splitting in strained WSe2 monolayers

Charting the Exciton–Polariton Landscape of WSe2 Thin Flakes by Cathodoluminescence Spectroscopy

Energy Scaling of Compositional Disorder in Ternary Transition‐Metal Dichalcogenide Monolayers

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Charting the Exciton–Polariton Landscape of WSe₂ Thin Flakes by Cathodoluminescence Spectroscopy