Structural and electronic properties of tungsten nanoclusters by DFT and basin-hopping calculations

Lin, Ken‐Huang; Wang, Shiliang; Chen, Chuan; Ju, Shin‐Pon

doi:10.1039/c4ra02053g

Cited by 6 publications

(4 citation statements)

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“…Higher impurity levels will also increase the heterogeneous nucleation density. Additionally, the breakdown of the molecular precursors in chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD) requires a high activation energy, slowing down the growth process [60][61][62]. All of these modifications result in a 'shifting' of the experimental conditions to a region of higher temper ature and a higher flux (pressure), yet the underlying concepts remain the same as described throughout this work.…”

Section: Order Of Magnitude Improvement In Grain Size and Path To Lar...mentioning

confidence: 97%

“…with the reaction energy diagram shown in figure 2(b) [60]. In this study, only atomic precursors are included, since the strong binding energy of clusters of the metal or chalcogen requires an overly high activation energy (5.44 eV for W-dimers and 4.64 eV for Se dimers) to participate in the epitaxial process [61,62]. Atoms arriving at the substrate surface, rather than being reflected back into the ambient, have a probability of being adsorbed on the surface.…”

Section: Kinetics and Thermodynamics Of Nucleus Formation And Critica...mentioning

confidence: 99%

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Nucleation and growth of WSe ₂ : enabling large grain transition metal dichalcogenides

et al. 2017

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The limited grain size (<200 nm) for transition metal dichalcogenides (TMDs) grown by molecular beam epitaxy (MBE) reported in the literature thus far is unsuitable for high-performance device applications. In this work, the fundamental nucleation and growth behavior of WSe 2 is investigated through a detailed experimental design combined with on-lattice, diffusion-based first principles kinetic modeling to enable large area TMD growth. A three-stage adsorption-diffusion-attachment mechanism is identified and the adatom stage is revealed to play a significant role in the nucleation behavior. To limit the nucleation density and promote 2D layered growth, it is necessary to have a low metal flux in conjunction with an elevated substrate temperature. At the same time, providing a Serich environment further limits the formation of W-rich nuclei which suppresses vertical growth and promotes 2D growth. The fundamental understanding gained through this investigation has enabled an increase of over one order of magnitude in grain size for WSe 2 thus far, and provides valuable insight into improving the growth of other TMD compounds by MBE and other growth techniques such as chemical vapor deposition (CVD).

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Section: Order Of Magnitude Improvement In Grain Size and Path To Lar...mentioning

confidence: 97%

Section: Kinetics and Thermodynamics Of Nucleus Formation And Critica...mentioning

confidence: 99%

Nucleation and growth of WSe ₂ : enabling large grain transition metal dichalcogenides

et al. 2017

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“…In general, point defects can increase average bond length and thus result in reduction in elastic modulus . Recent theoretical calculations and simulations suggested that the elastic moduli of many NWs decreased significantly with the increase in vacancy densities, including SiC, GaN, Si, W, Ag, Au and Cu . Experimental results also indicated that vacancies might be one of the important reasons for the relatively low modulus values of the NWs.…”

Section: Mechanical Characterization Of Nwsmentioning

confidence: 99%

The Mechanical Properties of Nanowires

2017

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Applications of nanowires into future generation nanodevices require a complete understanding of the mechanical properties of the nanowires. A great research effort has been made in the past two decades to understand the deformation physics and mechanical behaviors of nanowires, and to interpret the discrepancies between experimental measurements and theoretical predictions. This review focused on the characterization and understanding of the mechanical properties of nanowires, including elasticity, plasticity, anelasticity and strength. As the results from the previous literature in this area appear inconsistent, a critical evaluation of the characterization techniques and methodologies were presented. In particular, the size effects of nanowires on the mechanical properties and their deformation mechanisms were discussed.

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“…Now we discuss the nucleation mechanism without a pre‐seeding strategy. In a common thermal CVD, that is, WSe 2 growth from the reaction of WO x and Se vapors, the homogeneous nucleation 40 occurs with the incorporation of W clusters 69 and Se clusters 70 . Such a nucleus formation requires a complicated process, including the precursor decomposition, atom adsorption/desorption, adatom diffusion, adatom pinning at defect sites, bonds formation between adatoms, and clustering 71 …”

Section: Discussionmentioning

confidence: 99%

High‐performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre‐seeding strategy

Zhang

Pang

Cheng

et al. 2021

InfoMat

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Tungsten diselenide (WSe2) possesses extraordinary electronic properties for applications in electronics, optoelectronics, and emerging exciton physics. The synthesis of monolayer WSe2 film is of topmost for device arrays and integrated circuits. The monolayer WSe2 film has yet been reported by thermal chemical vapor deposition (CVD) approach, and the nucleation mechanism remains unclear. Here, we report a pre‐seeding strategy for finely regulating the nuclei density at an early stage and achieving a fully covered film after chemical vapor deposition growth. The underlying mechanism is heterogeneous nucleation from the pre‐seeding tungsten oxide nanoparticles. At first, we optimized the precursor concentration for pre‐seeding. Besides, we confirmed the superiority of the pre‐seeding method, compared with three types of substrate pretreatments, including nontreatment, sonication in an organic solvent, and oxygen plasma. Eventually, the high‐quality synthetic WSe2 monolayer film exhibits excellent device performance in field‐effect transistors and photodetectors. We extracted thermodynamic activation energy from the nucleation and growth data. Our results may shed light on the wafer‐scale production of homogeneous monolayer films of WSe2, other 2D materials, and their van der Waals heterostructures.

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Structural and electronic properties of tungsten nanoclusters by DFT and basin-hopping calculations

Abstract: The structural and electronic properties of small tungsten nanoclusters Wn (n = 2–16) were investigated by density functional theory (DFT) calculations.

Cited by 6 publications

References 53 publications

Nucleation and growth of WSe ₂ : enabling large grain transition metal dichalcogenides

Nucleation and growth of WSe ₂ : enabling large grain transition metal dichalcogenides

The Mechanical Properties of Nanowires

High‐performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre‐seeding strategy

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Structural and electronic properties of tungsten nanoclusters by DFT and basin-hopping calculations

Abstract: The structural and electronic properties of small tungsten nanoclusters Wn (n = 2–16) were investigated by density functional theory (DFT) calculations.

Cited by 6 publications

References 53 publications

Nucleation and growth of WSe 2 : enabling large grain transition metal dichalcogenides

Nucleation and growth of WSe 2 : enabling large grain transition metal dichalcogenides

The Mechanical Properties of Nanowires

High‐performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre‐seeding strategy

Contact Info

Product

Resources

About

Nucleation and growth of WSe ₂ : enabling large grain transition metal dichalcogenides

Nucleation and growth of WSe ₂ : enabling large grain transition metal dichalcogenides