Electronic and optical properties of vacancy-doped WS2 monolayers

Wei, Jianwei; Ma, Zengwei; Zeng, Hongtao; Wang, Zhi-Yong; Wei, Qiang; Peng, Ping

doi:10.1063/1.4768261

Cited by 48 publications

(41 citation statements)

References 28 publications

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“…Recent experimental as well as theoretical studies have demonstrated that sulfur vacancies are the dominant source of disorder in MoS 2 [13][14][15][16][17][18]. In the following we will therefore focus exclusively on sulfur vacancies, and calculate their effect on the VHC.…”

Section: Disordered Mosmentioning

confidence: 99%

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Valley Hall effect in disordered monolayerMoS2from first principles

Olsen

Souza

2015

Phys. Rev. B

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Electrons in certain two-dimensional crystals possess a pseudospin degree of freedom associated with the existence of two inequivalent valleys in the Brillouin zone. If, as in monolayer MoS 2 , inversion symmetry is broken and time-reversal symmetry is present, equal and opposite amounts of k-space Berry curvature accumulate in each of the two valleys. This is conveniently quantified by the integral of the Berry curvature over a single valley-the valley Hall conductivity. We generalize this definition to include contributions from disorder described with the supercell approach, by mapping ("unfolding") the Berry curvature from the folded Brillouin zone of the disordered supercell onto the normal Brillouin zone of the pristine crystal, and then averaging over several realizations of disorder. We use this scheme to study from first principles the effect of sulfur vacancies on the valley Hall conductivity of monolayer MoS 2 . In dirty samples the intrinsic valley Hall conductivity receives gating-dependent corrections that are only weakly dependent on the impurity concentration, consistent with side-jump scattering and the unfolded Berry curvature can be interpreted as a k-space resolved side jump. At low impurity concentrations skew scattering dominates, leading to a divergent valley Hall conductivity in the clean limit. The implications for the recently observed photoinduced anomalous Hall effect are discussed.

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Section: Disordered Mosmentioning

confidence: 99%

“…It is well established that sulfur vacancies constitute the main source of disorder in MoS 2 [13][14][15][16][17][18]. The formation energies and thermodynamics of these defects have been thoroughly studied [19], but their influence on transport and optical properties remains largely unexplored.…”

Section: Monolayers Of Mosmentioning

confidence: 99%

Valley Hall effect in disordered monolayerMoS2from first principles

Olsen

Souza

2015

Phys. Rev. B

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“…Similar exfoliation in aqueous solution instead of organic solvents has also been reported [15]. However, defect-free WS2 has been difficult to obtain, and imperfections including sulfur vacancy defects and oxidized impurities may strongly affect the transport properties of the materials [16,17]. In our previous work, we have developed a facile low-temperature thiol chemistry route to repair the sulfur vacancies and improve the electrical properties [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Facile Sonication Synthesis of WS2 Quantum Dots for Photoelectrochemical Performance

Zhou

Yan

et al. 2017

Catalysts

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Two-dimensional transition metal dichalcogenides, such as tungsten disulfide (WS 2 ), have been actively studied as suitable candidates for photocatalysts due to their unique structural and electronic properties. The presence of active sites at the edges and the higher specific surface area of these materials are crucial to the photocatalytic activity of the hydrogen evolution reaction. Here, WS 2 quantum dots (QDs) have been successfully synthesized by using a combination of grinding and sonication techniques. The morphology of the QDs was observed, using transmission electron microscopy and an atomic force microscope, to have uniform sizes of less than 5 nm. Photoelectrochemical (PEC) measurements show that the current density of WS 2 QDs under illumination is almost two times higher than that of pristine WS 2 . Furthermore, these high-quality WS 2 QDs may have various applications in optoelectronics, solar cells, and biomedicine.

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“…Furthermore, adatom adsorption and doping on ML MX 2 is especially achievable by virtue of their 2D surface nature. Both the naturally occurring and chemically or physically introduced point defects in MX 2 will extensively modulate the physical properties such as charge transport, magnetism, optical absorption, and absorbability [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], thus control the applicability of the material. The crucial role of point defects has triggered many studies to investigate their behavior in ML MX 2 .…”

Section: Introductionmentioning

confidence: 99%

Strong spin-orbit splitting and magnetism of point defect states in monolayer WS2

Fang

Huis

2016

Phys. Rev. B

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The spin-orbit coupling (SOC) effect has been known to be profound in monolayer pristine transition metal dichalcogenides (TMDs). Here we show that point defects, which are omnipresent in the TMD membranes, exhibit even stronger SOC effects and change the physics of the host materials drastically. In this article we chose the representative monolayer WS 2 slabs from the TMD family together with seven typical types of point defects including monovacancies, interstitials, and antisites. We calculated the formation energies of these defects, and studied the effect of spin-orbit coupling (SOC) on the corresponding defect states. We found that the S monovacancy (V S ) and S interstitial (adatom) have the lowest formation energies. In the case of V S and both of the W S and W S2 antisites, the defect states exhibit strong splitting up to 296 meV when SOC is considered. Depending on the relative position of the defect state with respect to the conduction band minimum (CBM), the hybrid functional HSE will either increase the splitting by up to 60 meV (far from CBM), or decrease the splitting by up to 57 meV (close to CBM). Furthermore, we found that both the W S and W S2 antisites possess a magnetic moment of 2 μ B localized at the antisite W atom and the neighboring W atoms. The dependence of SOC on the orientation of the magnetic moment for the W S and W S2 antisites is discussed. All these findings provide insights in the defect behavior under SOC and point to possibilities for spintronics applications for TMDs.

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Electronic and optical properties of vacancy-doped WS2 monolayers

Cited by 48 publications

References 28 publications

Valley Hall effect in disordered monolayerMoS2from first principles

Valley Hall effect in disordered monolayerMoS2from first principles

Facile Sonication Synthesis of WS2 Quantum Dots for Photoelectrochemical Performance

Strong spin-orbit splitting and magnetism of point defect states in monolayer WS2

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