An XPS study of the surface modification of natural MoS2 following treatment in an RF-oxygen plasma

Brown, N. M. D.; Cui, Nai-Yi; McKinley, A

doi:10.1016/s0169-4332(98)00252-9

Cited by 162 publications

(129 citation statements)

References 19 publications

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“…The observed binding energies are among those reported for thin 2H-MoS 2 layers and films (231.6 to 233.2 eV for Mo 3d 3/2 ). [39,40,43,44,[47][48][49]51,52] In addition, about 10% of the molybdenum was present as oxidized MoO 3 (Mo 6+ ) with binding energies [79] of 233.4 and 236.6 eV for Mo 3d 5/2 and Mo 3d 3/2 , respectively. This implies that the film surface is at least partially oxidized in air.…”

Section: Compositionmentioning

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

106

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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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Section: Compositionmentioning

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

106

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“…Introducing the TMDC film into a radio-frequency oxygen plasma generator for several minutes oxidizes the upper part of the TMDC film. [21] The film is now a bilayer consisting of the TMDC and the corresponding oxide. The chemical composition and the thickness of the oxide layer were determined by XPS.…”

mentioning

confidence: 99%

Novel Electrodes from Solution-Processed Layer-Structure Materials

Frey

Reynolds

Friend³

2002

Adv. Mater.

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“…However, for irradiated samples, a new peak at *235.0 eV which is attributed to Mo 6? state [18] appears at the fluence of 5 9 10 11 ions/cm 2 and quickly increases with increasing fluence. The increase in oxygen concentration and the appearance of higher oxidized Mo 6? state indicate that broken-bonds at latent tracks adsorb oxygen molecules in air.…”

Section: Xps Spectroscopymentioning

confidence: 97%

Swift-heavy ion irradiation-induced latent tracks in few- and mono-layer MoS2

et al. 2016

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The latent tracks in mono-and few-layer molybdenum disulfide (MoS 2 ) induced by 209 Bi ions with energies of 0.45-1.23 GeV were characterized by atomic force microscopy (AFM). The hillock-like latent tracks were observed on the surface of irradiated monolayer MoS 2 . The diameter of the hillock after deconvolution procedure is 15.8 ± 1.7 nm and the height is 1.0 ± 0.3 nm. Hillock-like tracks are induced by energy transfer from energetic 209 Bi ions to electron system of MoS 2 , resulting in the ionization and excitation and then the displacement of target atoms. Since Raman spectroscopy is sensitive to damages induced by swift-heavy ion irradiation, the in-plane E 2g 1 mode (*385 cm -1 ) and the out-of-plane A 1g mode (*408 cm -1 ) of MoS 2 were investigated. With increasing ion fluence, the A 1g peak shifts to higher frequencies, and the intensity ratio between A 1g and E 2g 1 peak increases. Besides, the A 1g peak narrows. The evolution of the structural and vibrational properties of MoS 2 with fluence is discussed. It can be concluded that the blue shift and narrowing of A 1g peak in irradiated MoS 2 is due to the adsorption of oxygen molecules at latent tracks. With decreasing thickness of MoS 2 , the irradiation resistance decreases.

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An XPS study of the surface modification of natural MoS2 following treatment in an RF-oxygen plasma

Cited by 162 publications

References 19 publications

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

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

Novel Electrodes from Solution-Processed Layer-Structure Materials

Swift-heavy ion irradiation-induced latent tracks in few- and mono-layer MoS2

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An XPS study of the surface modification of natural MoS2 following treatment in an RF-oxygen plasma

Cited by 162 publications

References 19 publications

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

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

Novel Electrodes from Solution-Processed Layer-Structure Materials

Swift-heavy ion irradiation-induced latent tracks in few- and mono-layer MoS2

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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

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