Exciton tuning in monolayer WSe<sub>2</sub><i>via</i>substrate induced electron doping

Pan, Yang; Rahaman, Mahfujur; He, Lu; Milekhin, Ilya; Manoharan, Gopinath; Aslam, Muhammad Awais; Blaudeck, Thomas; Willert, Andreas; Matković, Aleksandar; Madeira, Teresa I.; Zahn, Dietrich R. T.

doi:10.1039/d2na00495j

Cited by 11 publications

(11 citation statements)

References 69 publications

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“…Interestingly, the PL spectra of 1-L WSe 2 on Si–Au NPs show red-shifted X 0 and X T peaks, compared to the peaks observed on the 1-L WSe 2 on Si NPs. This redshift is attributed to the p -type doping of 1-L WSe 2 due to electron transfer to Au . In addition, the PL intensity of the X 0 peak was higher than that of the X T peak.…”

Section: Resultsmentioning

confidence: 99%

“…This redshift attributed to the p-type doping of 1-L WSe 2 due to electron transfer to Au. 72 In addition, the PL intensity of the X 0 peak was higher than that of the X T peak. This is caused by the transfer of electrons from 1-L WSe 2 to Au, which increases the hole concentration, resulting in a higher radiative recombination rate for X 0 and a lower intensity for X T emission.…”

Section: Optical Characterizationmentioning

confidence: 95%

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Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide

Jeong,

Nomenyo,

et al. 2024

ACS Nano

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Two-dimensional transition-metal dichalcogenides have attracted significant attention because of their unique intrinsic properties, such as high transparency, good flexibility, atomically thin structure, and predictable electron transport. However, the current state of device performance in monolayer transition-metal dichalcogenide-based optoelectronics is far from commercialization, because of its substantial strain on the heterogeneous planar substrate and its robust metal deposition, which causes crystalline damage. In this study, we show that strain-relaxed and undamaged monolayer WSe 2 can improve a device performance significantly. We propose here an original point-cell-type photodetector. The device consists in a monolayer of an absorbing TMD (i.e., WSe 2 ) simply deposited on a structured electrode, i.e., core−shell silicon−gold nanopillars. The maximum photoresponsivity of the device is found to be 23.16 A/W, which is a significantly high value for monolayer WSe 2 -based photodetectors. Such point-cell photodetectors can resolve the critical issues of 2D materials, leading to tremendous improvements in device performance.

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Section: Resultsmentioning

confidence: 99%

Section: Optical Characterizationmentioning

confidence: 95%

Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide

Jeong,

Nomenyo,

et al. 2024

ACS Nano

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“…We believe that the deep knowledge of the optical properties (i.e. dielectric function and PL) of hBN-encapsulated vdW homo-and heterostacks by means of spectroscopies with a resolution at the microand nanoscale [85,86] is pivotal for their exploitation in novel devices.…”

Section: Resultsmentioning

confidence: 99%

Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Ferrera

Sharma²,

Milekhin³

et al. 2023

J. Phys.: Condens. Matter

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Hexagonal boron nitride (hBN), sometimes referred to as white graphene, receives growing interest in the scientific community, especially when combined into van der Waals homo- and heterostacks, in which novel and interesting phenomena may arise. hBN is also commonly used in combination with 2D semiconducting transition metal dichalcogenides (TMDCs). The realization of hBN-encapsulated TMDC homo- and heterostacks can indeed offer opportunities to investigate and compare TMDC excitonic properties in various stacking configurations. In this work, we investigate the optical response at the micrometric scale of mono- and homo-bilayer WS2 grown by chemical vapor deposition and encapsulated between two single layers of hBN. Imaging spectroscopic ellipsometry (ISE) is exploited to extract the local dielectric functions across one single WS2 flake and detect the evolution of excitonic spectral features from monolayer to bilayer regions. Exciton energies undergo a redshift by passing from hBN-encapsulated single layer to homo-bilayer WS2, as also confirmed by photoluminescence spectra. Our results can provide a reference for the study of the dielectric properties of more complex systems where hBN is combined with other 2D van der Waals materials into heterostructures and are stimulating towards the investigation of the optical response of other technologically-relevant heterostacks.

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“…12 It has been demonstrated that morphological and structural arrangements of nanomaterials play crucial roles in their properties, and therefore the performance of devices can be regulated by precisely controlling morphology and structure. 13−19 Various techniques have been explored to manipulate the excitonic and electronic characteristics of monolayer TMDs, including strain, 20,21 layer-dependent engineering, 22 electron doping, 23,24 plasma treatment, 25 alterations in dielectric environments, 26 and the application of external electric fields. 27 Within the realm of TMDs, monolayer WSe 2 has gained prominence due to its potential as a single-photon source 28,29 and its relevance to quantum information processing, 30−32 attributed to its optical dark exciton ground state.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Notably, monolayer TMDs can exhibit direct band gap properties and emit bright photoluminescence (PL), − positioning them as clear candidates for next-generation optoelectronic devices . It has been demonstrated that morphological and structural arrangements of nanomaterials play crucial roles in their properties, and therefore the performance of devices can be regulated by precisely controlling morphology and structure. − Various techniques have been explored to manipulate the excitonic and electronic characteristics of monolayer TMDs, including strain, , layer-dependent engineering, electron doping, , plasma treatment, alterations in dielectric environments, and the application of external electric fields …”

Section: Introductionmentioning

confidence: 99%

Strain-Dependent Optical Properties of Monolayer WSe₂

Lv,

Abid,

Cheng

et al. 2023

J. Phys. Chem. C

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Monolayer WSe 2 exhibits a fascinating optical dark exciton ground state, which holds significant promise for advancing single-photon source and quantum information processing. In this study, we systematically explored the temperature-and straindependent optical properties of monolayer WSe 2 using a threedimensional silicon-based nanowrinkle structure as a template. We observed emission from a variety of excitonic states, including bright exciton (X 0 ), bright trion (X T ), dark exciton (X D ), and dark trion (X DT ), all originating from the same sample. Notably, we can selectively control and enhance their emissions. At a temperature of 153 K, the dominant emission source was the bright exciton, but as the mechanical compressive strain decreased to less than −0.015% at 105 K, dark excitons began to dominate the emission. Furthermore, when the mechanical strain was tensile and exceeded 0.03%, the intensities and energies of bright exciton (X 0 ), bright trion (X T ), dark exciton (X D ), and dark trion (X DT ) remained stable, indicating that all the excitons are drawn toward regions with the highest local strain due to a funneling effect. Additionally, we found that the expansion coefficient and Debye temperature of monolayer WSe 2 were critically influenced by the strain distribution. Specifically, the expansion coefficient tripled as the strain increased from a compressive −0.05% to a tensile 0.05% strain, and the Debye temperature increased from 20 to 600 K. Considering the compatibility of silicon-based substrates and monolayer transition metal dichalcogenides with semiconductor and photonic circuits, our approach holds promise for achieving site-controlled quantum emission of specific excitons and creating high-density quantum emitters through strain engineering.

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Exciton tuning in monolayer WSe₂viasubstrate induced electron doping

Abstract: We report on large exciton tuning in WSe2 monolayers via substrate induced non-degenerate doping. We observe a redshift of ∼62 meV for the A exciton together with a 1-2 orders...

Cited by 11 publications

References 69 publications

Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide

Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide

Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Strain-Dependent Optical Properties of Monolayer WSe₂

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Exciton tuning in monolayer WSe2viasubstrate induced electron doping

Abstract: We report on large exciton tuning in WSe2 monolayers via substrate induced non-degenerate doping. We observe a redshift of ∼62 meV for the A exciton together with a 1-2 orders...

Cited by 11 publications

References 69 publications

Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide

Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide

Local dielectric function of hBN-encapsulated WS2 flakes grown by chemical vapor deposition

Strain-Dependent Optical Properties of Monolayer WSe2

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Exciton tuning in monolayer WSe₂viasubstrate induced electron doping

Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Strain-Dependent Optical Properties of Monolayer WSe₂