Preferential hole defect formation in monolayer 
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 by electron-beam irradiation

Shin, Donghan; Wang, Gang; Han, Minmin; Lin, Zeyu; O’Hara, Andrew; Chen, Feiyu; Lin, Junhao; Pantelides, Sokrates T.

doi:10.1103/physrevmaterials.5.044002

Cited by 5 publications

(6 citation statements)

References 42 publications

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“…This is opposite to the case of WSe 2 , where the trefoil defect is stabilized by 1.31 eV and furthermore also has a reduced energy barrier of 3.12 eV, explaining why they are readily formed at room temperature [35]. The partial trefoil defect in WS 2 is also predicted to be unstable with a positive formation energy of 0.14 eV relative to a cluster of two sulfur divacancies [36]. Furthermore, the prerequisite for the formation of a trefoil defect is the clustering of chalcogen divacancies, requiring sufficiently mobile sulfur vacancies.…”

Section: Resultsmentioning

confidence: 78%

Radiation damage and defect dynamics in 2D WS₂: a low-voltage scanning transmission electron microscopy study

Graaf

Kooi

2021

2D Mater.

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Modern low-voltage scanning transmission electron microscopes (STEMs) have been invaluable for the atomic scale characterization of two-dimensional (2D) materials. Nevertheless, the observation of intrinsic structures of semiconducting and insulating 2D materials with 60 kV-microscopes has remained problematic due to electron radiation damage. In recent years, ultralow-voltage microscopes have been developed with the prospects of minimizing radiation damage of such 2D materials, however, to date only ultralow-voltage TEM investigations of semiconducting and insulating 2D materials have been reported, but similar results using STEM, despite being more widely adopted, are still missing. Here we report a quantitative analysis of radiation damage and beam-induced defect dynamics in semiconducting 2D WS2 during 30 kV and 60 kV-STEM imaging, particularly by recording atomic resolution electrostatic potential movies using integrated differential phase contrast to visualize both the light sulfur and heavy tungsten atoms. Our results demonstrate that electron radiation damage of 2D WS2 aggravates by a factor of two when halving the electron beam energy from 60 keV to 30 keV, from which we conclude electronic excitation and ionization to be the dominant mechanism inducing defects and damage during low-voltage STEM imaging of semiconducting 2D materials.

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Section: Resultsmentioning

confidence: 78%

Radiation damage and defect dynamics in 2D WS₂: a low-voltage scanning transmission electron microscopy study

Graaf

Kooi

2021

2D Mater.

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“…Although thermal properties of 2D materials are intensely investigated, [ 11–13,16–27 ] less is known about thermal conductivity of 2D Dirac materials [ 28 ] especially the impact of VHS on the energy carrier (electron and phonon) transport properties. High‐pressure technologies demonstrated great potential [ 29 ] for enriching the variety of 2D Dirac materials, which are rare compared with the numerous 2D materials.…”

Section: Introductionmentioning

confidence: 99%

“…Determining the properties of 2D matter in the one-atom-thin limit is a current frontier of science. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] One such emergent quantum phenomenon is the electronic transport through Dirac cones, which were first identified in graphene. [1][2][3] Close to the charge neutrality point, the graphene dispersion relation is linear and well described by the relativistic Dirac equation [4] with charge electronic structure.…”

Section: Introductionmentioning

confidence: 99%

Significant Increase of Electron Thermal Conductivity in Dirac Semimetal Beryllonitrene by Doping Beyond Van Hove Singularity

Tong

Pecchia

Yam

et al. 2022

Adv Funct Materials

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2D beryllium polynitrides or beryllonitrene is a newly synthesized layered material displaying anisotropic Dirac cones and van Hove singularity (VHS) located only ≈0.5 eV above the Fermi level. Using the Boltzmann transport equation with many-body effects and first-principles calculations, it is uncovered that beryllonitrene has an in-plane anisotropic room-temperature phonon thermal conductivity (κ ph ) of 78.6 and 98.8 W mK −1 , and an electron thermal conductivity (κ e ) of 23.0 and 60.7 W mK −1 , along the in-plane directions. κ ph is dominated by the large heat capacity flexural acoustic (ZA) modes, which are susceptible to three-phonon and four-phonon scatterings but rather immune to scattering onto electrons. Filling the Dirac cones till VHS and above gradually enhances the phonon-electron coupling and monotonically decreases κ ph by up to 55%. Instead, κ e displays unusual nonmonotonic variations with the increase in the carrier density and follows the electron density of states at corresponding Fermi levels. The results shed light on the thermal and electrical transport properties in beryllonitrene and reveal a thermal conductivity modulation mechanism that includes a 60% increase of κ e upon filling of the Dirac cones until VHS.

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“…39,40 Recent advances in defect engineering enable fine-tuning of defect density and species in TMDCs, 41−44 which is relevant for optimizing photogating and thus photodetection applications of graphene−TMDC heterostructures. For instance, V S can be either generated in a controlled fashion by electron beam irradiation 45 or chemically repaired by rational use of superacids and/or sulfur-containing agents. 46,47 The ability to precisely control the initial defect type/density and implement electrical control of E F and defect filling in graphene−TMDC heterostructures provides a new degree of freedom for manipulating interfacial dynamics at the vdW interface and developing high-performance optoelectronic devices.…”

mentioning

confidence: 99%

“…Sulfur vacancies are known to be prevalent in both exfoliated and CVD TMDCs due to their low formation energy. , Recent advances in defect engineering enable fine-tuning of defect density and species in TMDCs, − which is relevant for optimizing photogating and thus photodetection applications of graphene–TMDC heterostructures. For instance, V S can be either generated in a controlled fashion by electron beam irradiation or chemically repaired by rational use of superacids and/or sulfur-containing agents. , The ability to precisely control the initial defect type/density and implement electrical control of E F and defect filling in graphene–TMDC heterostructures provides a new degree of freedom for manipulating interfacial dynamics at the vdW interface and developing high-performance optoelectronic devices. On the other hand, rational passivation of V S and fabrication of undoped heterostructures can suppress defect-induced long-lived photogating at the interface, which is relevant for designing graphene–TMDC-based modulators with fast modulation speed and wide bandwidth.…”

mentioning

confidence: 99%

Reversible Electrical Control of Interfacial Charge Flow across van der Waals Interfaces

Jia

Hassan

et al. 2023

Nano Lett.

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Bond-free integration of two-dimensional (2D) materials yields van der Waals (vdW) heterostructures with exotic optical and electronic properties. Manipulating the splitting and recombination of photogenerated electron−hole pairs across the vdW interface is essential for optoelectronic applications. Previous studies have unveiled the critical role of defects in trapping photogenerated charge carriers to modulate the photoconductive gain for photodetection. However, the nature and role of defects in tuning interfacial charge carrier dynamics have remained elusive. Here, we investigate the nonequilibrium charge dynamics at the graphene−WS 2 vdW interface under electrochemical gating by operando optical-pump terahertz-probe spectroscopy. We report full control over charge separation states and thus photogating field direction by electrically tuning the defect occupancy. Our results show that electron occupancy of the two in-gap states, presumably originating from sulfur vacancies, can account for the observed rich interfacial charge transfer dynamics and electrically tunable photogating fields, providing microscopic insights for optimizing optoelectronic devices.

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Preferential hole defect formation in monolayer WSe2 by electron-beam irradiation

Cited by 5 publications

References 42 publications

Radiation damage and defect dynamics in 2D WS₂: a low-voltage scanning transmission electron microscopy study

Radiation damage and defect dynamics in 2D WS₂: a low-voltage scanning transmission electron microscopy study

Significant Increase of Electron Thermal Conductivity in Dirac Semimetal Beryllonitrene by Doping Beyond Van Hove Singularity

Reversible Electrical Control of Interfacial Charge Flow across van der Waals Interfaces

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Preferential hole defect formation in monolayer WSe2 by electron-beam irradiation

Cited by 5 publications

References 42 publications

Radiation damage and defect dynamics in 2D WS2: a low-voltage scanning transmission electron microscopy study

Radiation damage and defect dynamics in 2D WS2: a low-voltage scanning transmission electron microscopy study

Significant Increase of Electron Thermal Conductivity in Dirac Semimetal Beryllonitrene by Doping Beyond Van Hove Singularity

Reversible Electrical Control of Interfacial Charge Flow across van der Waals Interfaces

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Radiation damage and defect dynamics in 2D WS₂: a low-voltage scanning transmission electron microscopy study

Radiation damage and defect dynamics in 2D WS₂: a low-voltage scanning transmission electron microscopy study