Adhesion, Stiffness, and Instability in Atomically Thin MoS<sub>2</sub> Bubbles

Lloyd, D.; Liu, Xinghui; Boddeti, Narasimha; Cantley, Lauren; Long, Rong; Dunn, Martin L.; Bunch, J. Scott

doi:10.1021/acs.nanolett.7b01735

Cited by 103 publications

(125 citation statements)

References 53 publications

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“…More details on the CVD growth and transfer can be found in ref. [25]. The samples are kept in an atmosphere with a maximum pressure of 1 × 10 −6 mbar for two weeks before and during the experiment to ensure all gas has escaped from the cavity.…”

Section: Methodsmentioning

confidence: 99%

Transient thermal characterization of suspended monolayer MoS2

Dolleman

Lloyd

Lee

et al. 2018

Phys. Rev. Materials

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We measure the thermal time constants of suspended single layer molybdenum disulfide drums by their thermomechanical response to a high-frequency modulated laser. From this measurement the thermal diffusivity of single layer MoS2 is found to be 1.14 × 10 −5 m 2 /s on average. Using a model for the thermal time constants and a model assuming continuum heat transport, we extract thermal conductivities at room temperature between 10 to 40 W/(m·K). Significant device-to-device variation in the thermal diffusivity is observed. Based on statistical analysis we conclude that these variations in thermal diffusivity are caused by microscopic defects that have a large impact on phonon scattering, but do not affect the resonance frequency and damping of the membrane's lowest eigenmode. By combining the experimental thermal diffusivity with literature values of the thermal conductivity, a method is presented to determine the specific heat of suspended 2D materials, which is estimated to be 255 ± 104 J/(kg·K) for single layer MoS2.

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Section: Methodsmentioning

confidence: 99%

Transient thermal characterization of suspended monolayer MoS2

Dolleman

Lloyd

Lee

et al. 2018

Phys. Rev. Materials

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“…Bubbles of various shapes and sizes can be formed on 2D materials, such as graphene, BN, and MoS 2 , due to the impermeability, excellent flexibility, and exceptional mechanical strength of these atomically thin sheets. The bubbles have been proved to be a useful model to measure the adhesion energies, friction coefficient, stiffness, and Young's modulus of 2D materials, providing opportunity for understanding the adhesion and mechanical properties of these atomically thin materials. The bubbles of 2D materials have also been demonstrated to own potential applications in electronics and photonics .…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence and Raman Spectra Oscillations Induced by Laser Interference in Annealing‐Created Monolayer WS₂ Bubbles

Jia

Dong

Liu

et al. 2019

Advanced Optical Materials

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of 2D materials, [3][4][5] providing opportunity for understanding the adhesion and mechanical properties of these atomically thin materials. The bubbles of 2D materials have also been demonstrated to own potential applications in electronics and photonics. [6][7][8] For example, scanning tunneling microscopy measurements have verified the presence of enormous pseudo-magnetic fields in highly strained graphene nanobubbles, [7] offering a new basis for exploration of extremely high magnetic field regimes in a condensedmatter environment. Georgiou et al. [6] have demonstrated that the curvature of graphene can be tuned by applying an external electric field, showing potential application for optical lenses. Bao et al. [8] have reported that there is strong nonlinear light-matter interaction in graphene nanobubbles, resulting in optical bistability effect at cavity resonance. Interference-induced Raman enhancement [9] and oscillations [10] have also been observed in graphene bubbles.Like graphene, atomically thin WS 2 crystal is also a mechanically exceptional material, which can be grown or transferred on various substrates. [11][12][13][14] On top of that, it is semiconductor, undergoing a transition from indirect to direct bandgap after thinning to monolayer. [15] In addition, monolayer WS 2 shows strong photoluminescence (PL) with high efficiency and narrower emission linewidth. [16] Due to these superior properties, monolayer WS 2 has shown promising applications in electronics, spintronics, valleytronics, and optoelectronic, [17][18][19] such as field-effect transistors, [20,21] photodetectors, [22,23] magnetoluminescence devices, [24] and valleytronic devices. [25] Monolayer WS 2 crystal, whose bandgap and lattice vibrations are highly sensitive to external conditions like strain, [26,27] pressure, [28] temperature, [29,30] and electric field, [31] is also a perfect model material for PL and Raman studies. [16,32,33] Although numerous studies and research on atomically thin WS 2 crystals have been carried out, there has been no experimental observation on WS 2 bubble so far, much less its properties.In the present work, huge amount of monolayer WS 2 (1L WS 2 ) bubbles are created in large-scale CVD-grown WS 2 WS 2 monolayer crystals have been grown in a large scale by chemical vapor deposition on SiO 2 (300 nm)/Si substrates, and via high-temperature treatment under protection of Ar or N 2 gas flow after growth, huge amount of monolayer WS 2 bubbles have been successfully created in a shape of spherical cap and widely distributed sizes. Optical and fluorescence images reveal obvious interference rings on the monolayer WS 2 bubbles of large sizes. In line scans and mapping images of photoluminescence (PL) and Raman, oscillatory behaviors have been observed not only for peak intensity but also for peak position and width. It is easy to understand that the oscillatory PL and Raman peak intensities originate from constructive and destructive interference on the bubble's surface, while the oscillatory peak positio...

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“…The notable transformation of the electronic properties of transition‐metal dichalcogenides (TMDs) when reduced to a single X–M–X plane (X: chalcogen; M: metal) makes them suitable for flexible, innovative optoelectronic devices, and transistors . Like graphene, few‐layer TMDs can also withstand surprisingly large mechanical deformations, which, coupled to the material's electronic structure, would enable the observation of nondissipative topological transport, provided a periodic modulation of strain is attained . TMD monolayers (MLs) and nanostructures are also important for their catalytic role in the cost‐effective production of hydrogen .…”

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confidence: 99%

“…In fact, other methods for the creation of strained TMD bubbles either allow size/position controllability but lack durability (as in Refs. ) or permit to create durable structures lacking any spatial ordering (as in Ref. ), in both cases considerably limiting their potentiality for applications.…”

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confidence: 99%

Controlled Micro/Nanodome Formation in Proton‐Irradiated Bulk Transition‐Metal Dichalcogenides

et al. 2019

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The notable transformation of the electronic properties of transition-metal dichalcogenides (TMDs) when reduced to a single X-M-X plane (X: chalcogen; M: metal) [1] makes them suitable for flexible, innovative optoelectronic devices, [2][3][4] and transistors. [5] Like graphene, few-layer TMDs can also withstand surprisingly large mechanical deformations, [6][7][8][9] which, coupled to the material's electronic structure, would enable the observation of nondissipative topological transport, provided a periodic modulation of strain is attained. [10][11][12][13] TMD monolayers (MLs) and nanostructures are also important for their catalytic role in the cost-effective production of hydrogen. [14][15][16] These examples share the need to achieve spatial control of the material's properties, over sample regions with size ranging from the nano [14,16] to the micrometer [16] scale lengths.In this study, we present a route toward the patterning of TMDs based on the effects of low-energy proton irradiation [17] on the structural and electronic properties of bulk WS 2 , WSe 2 , WTe 2 , MoS 2 , MoSe 2 , and MoTe 2 . Suitable irradiation conditions trigger the production and accumulation of H 2 just beneath the first X-M-X basal plane, leading to the localized exfoliation of the topmost monolayer and to the formation of spherically shaped domes. Structural and optical characterizations confirm that these domes are typically one ML-thick and contain H 2 at pressures in the 10-100 atm range, depending on their size. Such high pressures induce strong and complex strain fields acting on the curved X-M-X planes, that are evaluated by means of a mechanical model. The domes' morphological characteristics can be tuned by lithographically controlling the area of the sample basal plane participating in the hydrogen production process. This results in the unprecedented fabrication of robust domes with controlled position/density and sizes tunable from the nanometer to the micrometer scale, that, by virtue of their inherently strained nature and geometry, might prompt a variety of applications.The samples, consisting of thick (tens to hundreds of MLs) TMD flakes, were obtained by mechanical exfoliation, deposited on Si substrates, and afterwards proton-irradiated using a Kaufman source (see the Experimental Methods). Differently from the other works in the literature concerning protonirradiation of TMDs-where beams with energies ≥10 5 eV are used, [18] aiming at the controlled formation of defects in the irradiated samples-here we irradiate the flakes with low energy At the few-atom-thick limit, transition-metal dichalcogenides (TMDs) exhibit strongly interconnected structural and optoelectronic properties. The possibility to tailor the latter by controlling the former is expected to have a great impact on applied and fundamental research. As shown here, proton irradiation deeply affects the surface morphology of bulk TMD crystals. Protons penetrate the top layer, resulting in the production and progressive accumulation of molecular hydr...

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Adhesion, Stiffness, and Instability in Atomically Thin MoS₂ Bubbles

Cited by 103 publications

References 53 publications

Transient thermal characterization of suspended monolayer MoS2

Transient thermal characterization of suspended monolayer MoS2

Photoluminescence and Raman Spectra Oscillations Induced by Laser Interference in Annealing‐Created Monolayer WS₂ Bubbles

Controlled Micro/Nanodome Formation in Proton‐Irradiated Bulk Transition‐Metal Dichalcogenides

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Adhesion, Stiffness, and Instability in Atomically Thin MoS2 Bubbles

Cited by 103 publications

References 53 publications

Transient thermal characterization of suspended monolayer MoS2

Transient thermal characterization of suspended monolayer MoS2

Photoluminescence and Raman Spectra Oscillations Induced by Laser Interference in Annealing‐Created Monolayer WS2 Bubbles

Controlled Micro/Nanodome Formation in Proton‐Irradiated Bulk Transition‐Metal Dichalcogenides

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Adhesion, Stiffness, and Instability in Atomically Thin MoS₂ Bubbles

Photoluminescence and Raman Spectra Oscillations Induced by Laser Interference in Annealing‐Created Monolayer WS₂ Bubbles