Effect of disorder on Raman scattering of single-layer<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Mo</mml:mi><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Mignuzzi, Sandro; Pollard, Andrew J.; Bonini, Nicola; Brennan, Barry; Gilmore, Ian S.; Pimenta, M. A.; Richards, David; Roy, Debdulal

doi:10.1103/physrevb.91.195411

Cited by 638 publications

(555 citation statements)

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“…Fitting the data in Figure 7D [47]. In addition to vacancy defects, oxygen substitution in TMDs can also be characterized by Raman spectroscopy.…”

Section: Defect Characterization In Tmds By Raman Spectroscopymentioning

confidence: 94%

“…Figure 7C shows the evolution of Raman spectra of monolayer MoS 2 as a function of L D , where L D is an average interdefect distance, which can be used for expressing the defect density. The L D of vacancy defects in monolayer MoS 2 flakes can be tuned by Mn + bombardment [47] with the relationship D L , 1/ σ = where σ is the ion dose density. As can be seen, several defect-activated peaks appear in MoS 2 samples.…”

Section: Defect Characterization In Tmds By Raman Spectroscopymentioning

confidence: 99%

“…These Raman peaks are activated by double-resonant intervalley and intravalley scattering processes, respectively, where a defect provides the missing momentum in order to satisfy momentum conservation in the Raman scattering process [45,46]. For TMDs, some new Raman peaks also appear after the introduction of defects, and their intensities are related to the density of defects [47], but the sensitivity is not very high. At same time, in low-temperature PL measurement, a defect-related PL peak of TMDs could be observed due to the emission of excitons bound to the defect sites, which could be effectively used to monitor the numbers of defects in TMDs [48].…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic investigation of defects in two-dimensional materials

2017

Nanophotonics

118

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Two-dimensional (2D) materials have been extensively studied in recent years due to their unique properties and great potential for applications. Different types of structural defects could present in 2D materials and have strong influence on their properties. Optical spectroscopic techniques, e.g. Raman and photoluminescence (PL) spectroscopy, have been widely used for defect characterization in 2D materials. In this review, we briefly introduce different types of defects and discuss their effects on the mechanical, electrical, optical, thermal, and magnetic properties of 2D materials. Then, we review the recent progress on Raman and PL spectroscopic investigation of defects in 2D materials, i.e. identifying of the nature of defects and also quantifying the numbers of defects. Finally, we highlight perspectives on defect characterization and engineering in 2D materials.

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“…Fitting the data in Figure 7D [47]. In addition to vacancy defects, oxygen substitution in TMDs can also be characterized by Raman spectroscopy.…”

Section: Defect Characterization In Tmds By Raman Spectroscopymentioning

confidence: 94%

Section: Defect Characterization In Tmds By Raman Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectroscopic investigation of defects in two-dimensional materials

2017

Nanophotonics

118

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“…As we observed asymmetric broadening of the MoS 2 peaks, we used the peak fitting strategy of Mignuzzi et al [77] to estimate disorder in the films. In addition to the E 1 2g and A 1g modes, three disorder-induced peaks were fitted, which originate from the transverse optical (≈355 cm −1 ), longitudinal optical (≈377 cm −1 ), and out-of-plane optical (≈412 cm −1 ) branches at the M point of the Brillouin zone (Figure 4c).…”

Section: Crystallinitymentioning

confidence: 99%

Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Mattinen

Hatanpää

Sarnet

et al. 2017

Adv Materials Inter

110

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Compared to the most well-known 2D material, graphene, which is a semi-metal, the semiconducting 2H phase of MoS 2 is advantageous in having a band gap suitable for electronic applications. In bulk form, MoS 2 has an indirect band gap of 1.3 eV, which increases as a function of decreasing film thickness. In monolayer MoS 2 (thickness ≈0.6 nm), the band gap becomes direct with a width of 1.8 eV. [1] Importantly, to meet the requirements of different applications, properties of MoS 2 and other TMDCs can be tuned by controlling the thickness, [1] doping and alloying, [5][6][7][8] surface modification and functionalization, [9][10][11] strain, [12,13] and by creating heterostructures with other 2D materials. [6,[14][15][16] The appealing properties of TMDCs have led to a wide range of proposed applications. MoS 2 has been extensively studied as a channel material in conventional field-effect transistors, [17][18][19][20][21] as well as phototransistors and other optoelectronic devices. [16,21,22] The 2D structure of TMDCs plays a crucial role in possible applications relying on more exotic quantum phenomena, such as valleytronics. [23,24] MoS 2 has also shown promise in, for example, catalysis, [25] batteries, [26] photovoltaics, [27] sensors, [28] and medicine. [29] The production of high-quality, large-area MoS 2 films with a thickness controllable down to a monolayer, as required in many of the aforementioned applications, still remains a major challenge. Additionally, in many cases, the processing temperature should be kept as low as possible in order to avoid damaging sensitive substrates, such as polymers or nanostructures. Initially, flakes of monolayer MoS 2 were produced from natural MoS 2 crystals using micromechanical exfoliation, a topdown method capable of producing high-quality monolayers, albeit with poor throughput as well as limited control over flake thickness and dimensions. [4,30,31] Liquid-phase exfoliation of bulk crystals, on the other hand, offers good scalability, but often suffers from limited flake size, poor crystallinity, or contamination. [4,31,32] Bottom-up methods offer a more controllable way to produce MoS 2 films. High-quality MoS 2 thin films are most commonly deposited by chemical vapor deposition (CVD) or sulfurization of metal or metal oxide thin films. The most common Molybdenum disulfide (MoS 2 ) is a semiconducting 2D material, which has evoked wide interest due to its unique properties. However, the lack of controlled and scalable methods for the production of MoS 2 films at low temperatures remains a major hindrance on its way to applications. In this work, atomic layer deposition (ALD) is used to deposit crystalline MoS 2 thin films at a relatively low temperature of 300 °C. A new molybdenum precursor, Mo(thd) 3 (thd = 2,2,6,6-tetramethylheptane-3,5-dionato), is synthesized, characterized, and used for film deposition with H 2 S as the sulfur precursor. Self-limiting growth with a low growth rate of ≈0.025 Å cycle −1 , straightforward thickness control, and large-area uni...

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“…We would like to mention that we do not see differences in the Raman spectra between the different samples indicating that the interdefect distance in all samples is larger than approx. 5 nm [70].…”

Section: Electrochemical Characterization Without Illuminationmentioning

confidence: 99%

Hydrogen evolution activity of individual mono-, bi-, and few-layer MoS 2 towards photocatalysis

Parzinger

Mitterreiter

Stelzer

et al. 2017

Applied Materials Today

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b s t r a c tWe investigate the hydrogen evolution activity in the dark and under illumination above the band gap of individual mono-, bi-and few-layer (bulk) MoS 2 flakes. We demonstrate that the electrocatalytic activity of 2H-MoS 2 immersed in 1 M H 2 SO 4 increases with decreasing number of layers. For monolayers, we observe the highest exchange current density, which is one magnitude larger than in the bulk case. The onset potential scales with the number of layers, which is consistent with a previous report, suggesting that hopping transport across inter-layer barriers within the MoS 2 flakes is responsible for this scaling.A specially designed micro-sized catalytic cell enables us to investigate individual MoS 2 flakes with well-known geometry and edge-to-surface ratio. Taking these geometric parameters into account, we tentatively attribute the catalytic activity mainly to sulfur vacancies in the basal planes acting as active sites. The associated turn over frequencies (TOF) for mono-and bi-layer MoS 2 yield values higher than 10 3 s −1 at an overpotential of −0.2 V vs. RHE. In view of light driven hydrogen evolution as a means of solar energy conversion, we investigate the photocatalytic activity of few-layer MoS 2 under white light illumination.

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Effect of disorder on Raman scattering of single-layerMoS2

Cited by 638 publications

References 46 publications

Spectroscopic investigation of defects in two-dimensional materials

Spectroscopic investigation of defects in two-dimensional materials

Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Hydrogen evolution activity of individual mono-, bi-, and few-layer MoS 2 towards photocatalysis

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Effect of disorder on Raman scattering of single-layerMoS2

Cited by 638 publications

References 46 publications

Spectroscopic investigation of defects in two-dimensional materials

Spectroscopic investigation of defects in two-dimensional materials

Atomic Layer Deposition of Crystalline MoS2 Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Hydrogen evolution activity of individual mono-, bi-, and few-layer MoS 2 towards photocatalysis

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Product

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Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth