Telluriding monolayer MoS2 and WS2 via alkali metal scooter

Yun, Seok Joon; Han, Gang; Kim, Hyun; Duong, Dinh Loc; Shin, Bong Gyu; Zhao, Jiong; Vu, Quoc An; Lee, Jubok; Lee, Seung Mi; Lee, Young Hee

doi:10.1038/s41467-017-02238-0

Cited by 93 publications

(53 citation statements)

References 33 publications

(32 reference statements)

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“…The microscopic mechanism of CVD is that the precursor of gas/vapor phase nucleates and then regenerates into films on the substrate [19]. A new molten salt-assisted CVD method for growing TMDCs has recently attracted attention [20][21][22][23][24][25]. The introduction of alkali metal promoter can effectively enhance the lateral growth of the film, making it a unique method for obtaining large-size single crystals.…”

Section: Introductionmentioning

confidence: 99%

Aligned monolayer MoS2 ribbons growth on sapphire substrate via NaOH-assisted chemical vapor deposition

Zhan

et al. 2020

Sci. China Mater.

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This study reports the growth of aligned monolayer molybdenum disulfide (MoS 2) ribbons on a sapphire substrate via NaOH-assisted chemical vapor deposition. The length of MoS 2 ribbon is up to 400 μm. The MoS 2 ribbon has excellent single crystal properties, a carrier mobility of1 50 cm 2 V −1 s −1 , and a optical response of 103 mA W −1 at a wavelength of 550 nm. The growth model of MoS 2 ribbons was given. NaOH reacts with MoO 3 to form sodium molybdate droplets, which increase the fluidity of the molybdenum source on the substrate, realizing the vapor-liquid-solid growth of MoS 2 on sapphire. The monolayer MoS 2 ribbons have two kinds of arrangements on the sapphire substrate, one is the oriented growth affected by the interlayer van der Waals force and the lattice, and the other is the aligned growth constrained by the sapphire step. Our results promote the basic research and device applications of MoS 2 , and introduce a new way of synthesizing other one dimensional (1D) and 2D nanostructures.

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Section: Introductionmentioning

confidence: 99%

Aligned monolayer MoS2 ribbons growth on sapphire substrate via NaOH-assisted chemical vapor deposition

Zhan

et al. 2020

Sci. China Mater.

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“…Direct tellurization CVD has emerged as a viable alternative to vdWE for achieving continuous and high-area growth of MoTe 2 [24][25][26][27] . The process relies on a reaction (facilitated by the reductive flow of H 2 ) between Te vapour and an atomically thin seeding layer (commonly Mo-metal) pre-deposited on a substrate.…”

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confidence: 99%

Selective phase growth and precise-layer control in MoTe2

et al. 2020

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Minor structural changes in transition metal dichalcogenides can have dramatic effects on their electronic properties. This makes the quest for key parameters that enable a selective choice between the competing metallic and semiconducting phases in the 2D MoTe 2 system compelling. Herein, we report the optimal conditions at which the choice of the initial seed layer dictates the type of crystal structure of atomically-thin MoTe 2 films grown by chemical vapour deposition (CVD). When Mo metal is used as a seed layer, semiconducting 2H-MoTe 2 is the only product. Conversely, MoO 3 leads to the preferential growth of metallic 1T′-MoTe 2. The control over phase growth allows for simultaneous deposition of both 2H-MoTe 2 and 1T′-MoTe 2 phases on a single substrate during one CVD reaction. Furthermore, Rhodamine 6G dye can be detected using few-layered 1T′-MoTe 2 films down to 5 nM concentration, demonstrating surface enhanced Raman spectroscopy (SERS) with sensitivity several orders of magnitude higher than for bulk 1T′-MoTe 2 .

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“…Experiments on a WS 0.6 Se 1.4 alloy demonstrated a valley polarization of ≈31% at 14 K, which was much lower than that of both WS 2 and WSe 2 27 . A recent study of WS x Te 2− x found that the room temperature valley polarization increased from 3% in WS 2 to 37% in an unspecified alloy composition 28 . The limited information regarding valley polarization in alloyed TMDs is a serious oversight as future valleytronic technologies will likely rely heavily on band engineering.…”

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confidence: 98%

Valley phenomena in the candidate phase change material WSe2(1-x)Te2x

et al. 2020

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Alloyed transition metal dichalcogenides provide a unique opportunity for coupling band engineering and valleytronic phenomena in an atomically-thin platform. However, valley properties in alloys remain largely unexplored. We investigate the valley degree of freedom in monolayer alloys of the phase change candidate material WSe2(1-x)Te2x. Low temperature Raman measurements track the alloy-induced transition from the semiconducting 1H phase of WSe2 to the semimetallic 1Td phase of WTe2. We correlate these observations with density functional theory calculations and identify new Raman modes from 1H-WTe2. Photoluminescence measurements show ultra-low energy emission features that highlight the presence of significant alloy disorder arising from the large W-Te bond lengths. Interestingly, valley polarization and coherence in alloys survive at high Te compositions and are more robust against temperature than in WSe2. These findings illustrate the persistence of valley properties in alloys with highly dissimilar parent compounds and suggest band engineering can be utilized for valleytronic devices.

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Telluriding monolayer MoS2 and WS2 via alkali metal scooter

Cited by 93 publications

References 33 publications

Aligned monolayer MoS2 ribbons growth on sapphire substrate via NaOH-assisted chemical vapor deposition

Aligned monolayer MoS2 ribbons growth on sapphire substrate via NaOH-assisted chemical vapor deposition

Selective phase growth and precise-layer control in MoTe2

Valley phenomena in the candidate phase change material WSe2(1-x)Te2x

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