CVD grown 2D MoS<sub>2</sub> layers: A photoluminescence and fluorescence lifetime imaging study

Özden, Ayberk; Şar, Hüseyin; Yeltik, Aydan; Madenoğlu, Büşra; Sevik, Cem; Ay, F.; Perkgöz, Nihan Kosku

doi:10.1002/pssr.201600204

Cited by 26 publications

(18 citation statements)

References 24 publications

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“…The flake edge delamination from the substrate can reproduce such PL behavior as well. Similar domain contrast including the edge effects is universally discovered in a lot of TMD materials such as MoS 2 and WSe 2 . − It is also noted that the contrast between domains cannot be observed when the sample size gets smaller (<30 μm) (Figure d), especially for after-transfer samples. It is noteworthy that after the transfer process (both on silicon substrate) the PL intensity decreased by around 70% and the A exciton peaks have blue-shifted for both W-ZZ and S-ZZ domains, implying the release of tensile strain during transfer.…”

Section: Resultssupporting

confidence: 66%

Edge Delamination of Monolayer Transition Metal Dichalcogenides

Yun

Thi

et al. 2017

ACS Nano

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Delamination of thin films from the supportive substrates is a critical issue within the thin film industry. The emergent two-dimensional, atomic layered materials, including transition metal dichalcogenides, are highly flexible; thus buckles and wrinkles can be easily generated and play vital roles in the corresponding physical properties. Here we introduce one kind of patterned buckling behavior caused by the delamination from a substrate initiated at the edges of the chemical vapor deposition synthesized monolayer transition metal dichalcogenides, led by thermal expansion mismatch. The atomic force microscopy and optical characterizations clearly showed the puckered structures associated with the strain, whereas the transmission electron microscopy revealed the special sawtooth-shaped edges, which break the geometrical symmetry for the buckling behavior of hexagonal samples. The condition of the edge delamination is in accordance with the fracture behavior of thin film interfaces. This edge delamination and buckling process is universal for most ultrathin two-dimensional materials, which requires more attention in various future applications.

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Section: Resultssupporting

confidence: 66%

Edge Delamination of Monolayer Transition Metal Dichalcogenides

Yun

Thi

et al. 2017

ACS Nano

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“…The mode at 227 cm –1 is associated with the sample disorder, while a minor contribution from a MoO x mode can be observed at 996 cm –1 . (b) Correlation between E 2g 1 and A 1g mode spacing, and number of layers, using literature data. ,− …”

Section: Resultsmentioning

confidence: 99%

Colloidal Continuous Injection Synthesis of Fluorescent MoX₂ (X = S, Se) Nanosheets as a First Step Toward Photonic Applications

Pippia

Rousaki

Barbone

et al. 2022

ACS Appl. Nano Mater.

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Transition-metal dichalcogenide (TMD) nanosheets have become an intensively investigated topic in the field of 2D nanomaterials, especially due to the direct semiconductor nature, and the broken inversion symmetry in the odd-layer number, of some of their family members. These properties make TMDs attractive for different technological applications such as photovoltaics, optoelectronics, valleytronics, and hydrogen evolution reactions. Among them, MoX 2 (X = S and Se) are turned to direct gap when their thickness is thinned down to monolayer, and thus, efforts toward obtaining large-scale monolayer TMDs are crucial for technological applications. Colloidal synthesis of TMDs has been developed in recent years, as it provides a cost-efficient and scalable way to produce few-layer TMDs having homogeneous size and thickness, yet obtaining a monolayer has proven challenging. Here, we present a method for the colloidal synthesis of mono-and few-layer MoX 2 (X = S and Se) using elemental chalcogenide and metal chloride as precursors. Using a synthesis with slow injection of the MoCl 5 precursor under a nitrogen atmosphere, and optimizing the synthesis parameters with a design of experiments approach, we obtained a MoX 2 sample with the semiconducting (1H) phase and optical band gaps of 1.96 eV for 1H−MoS 2 and 1.67 eV for 1H−MoSe 2 , respectively, consistent with a large monolayer yield in the ensemble. Both display photoluminescence at cryogenic and room temperature, paving the way for optical spectroscopy studies and photonic applications of colloidal TMD nanosheets.

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“…However, if S was introduced only 4 min before the WO 3 precursor reaches the target temperature, the WS 2 domains became thicker and much smaller (20–30 μm in lateral size) . In contrast, in most of the reported works for CVD growth of WS 2 , S was introduced simultaneously with WO 3 , − corresponding to the case of “too late” in refs and . It is clear that the conditions for optimal CVD growth of monolayer WS 2 are very sensitive to the specific CVD configuration.…”

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confidence: 99%

WS₂ Nanotubes, 2D Nanomeshes, and 2D In-Plane Films through One Single Chemical Vapor Deposition Route

et al. 2019

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We demonstrate a versatile, catalyst free chemical vapor deposition process on insulating substrates capable of producing in one single stream one-dimensional (1D) WO3–x suboxides leading to a wide range of substrate-supported 2H-WS2 polymorphs: a tunable class of out-of-plane (of the substrate) nanophases, with 1D nanotubes and a pure WS2, two-dimensional (2D) nanomesh (defined as a network of webbed, micron-size, few-layer 2D sheets) at its extremes; and in-plane (parallel to the substrate) mono- and few-layer 2D domains. This entails a two-stage approach in which the 2WO3 + 7S → 2WS2 + 3SO2 reaction is intentionally decoupled. First, various morphologies of nanowires or nanorods of high stoichiometry, WO2.92/WO2.9 suboxides (belonging to the class of Magnéli phases) were formed, followed by their sulfurization to undergo reduction to the aforementioned WS2 polymorphs. The continuous transition of WS2 from nanotubes to the out-of-plane 2D nanomesh, via intermediary, mixed 1D-2D phases, delivers tunable functional properties, for example, linear and nonlinear optical properties, such as reflectivity (linked to optical excitations in the material), and second harmonic generation (SHG) and onset of saturable absorption. The SHG effect is very strong across the entire tunable class of WS2 nanomaterials, weakest in nanotubes, and strongest in the 2D nanomesh. Furthermore, a mechanism via suboxide (WO3–x ) intermediate as a possible path to 2D domain growth is demonstrated. 2D, in-plane WS2 domains grow via “self-seeding and feeding” where short WO2.92/WO2.9 nanorods provide both the nucleation sites and the precursor feedstock. Understanding the reaction path (here, in the W–O–S space) is an emerging approach toward controlling the nucleation, growth, and morphology of 2D domains and films of transition-metal dichalcogenides.

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CVD grown 2D MoS₂ layers: A photoluminescence and fluorescence lifetime imaging study

Cited by 26 publications

References 24 publications

Edge Delamination of Monolayer Transition Metal Dichalcogenides

Edge Delamination of Monolayer Transition Metal Dichalcogenides

Colloidal Continuous Injection Synthesis of Fluorescent MoX₂ (X = S, Se) Nanosheets as a First Step Toward Photonic Applications

WS₂ Nanotubes, 2D Nanomeshes, and 2D In-Plane Films through One Single Chemical Vapor Deposition Route

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CVD grown 2D MoS2 layers: A photoluminescence and fluorescence lifetime imaging study

Cited by 26 publications

References 24 publications

Edge Delamination of Monolayer Transition Metal Dichalcogenides

Edge Delamination of Monolayer Transition Metal Dichalcogenides

Colloidal Continuous Injection Synthesis of Fluorescent MoX2 (X = S, Se) Nanosheets as a First Step Toward Photonic Applications

WS2 Nanotubes, 2D Nanomeshes, and 2D In-Plane Films through One Single Chemical Vapor Deposition Route

Contact Info

Product

Resources

About

CVD grown 2D MoS₂ layers: A photoluminescence and fluorescence lifetime imaging study

Colloidal Continuous Injection Synthesis of Fluorescent MoX₂ (X = S, Se) Nanosheets as a First Step Toward Photonic Applications

WS₂ Nanotubes, 2D Nanomeshes, and 2D In-Plane Films through One Single Chemical Vapor Deposition Route