Mechanical removal of surface residues on graphene for TEM characterizations

Kim, Dong-Gyu; Lee, Sol; Kim, Kwanpyo

doi:10.1186/s42649-020-00048-1

Cited by 10 publications

(8 citation statements)

References 17 publications

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“…Recently, some works about direct growth of the 1-T (T') phase film occurred. [234,244] Xu et al used magnetron sputtering to deposit a thin film of Mo and tellurized it to get few-layer metallic 1T'-MoTe 2 in wafer scale. It is found when growth time increases, the 1T'-MoTe 2 converts to 2H-MoTe 2 .…”

Section: Phasementioning

confidence: 99%

Toward Wafer‐Scale Production of 2D Transition Metal Chalcogenides

Wang

Yang

2021

Adv Elect Materials

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When the timeline reached 2004, graphene, the single layer of graphite, was discovered through a scotch-tape exfoliation method and was found to have ultrahigh mobility. [25][26][27] Various 2D materials such as transition metal chalcogenides (TMCs), [28][29][30] boron nitrides (BNs), [31,32] black phosphorus, [33,34] and some new materials including Si, [35] Te, [36] and black arsenic-phosphorus [37] were subsequently synthesized, enabling the fabrication of numerous novel devices. The field of 2D materials is now making strong voice, which is no longer ignored by the scientific and technological community. [38][39][40] Among the various 2D materials, the TMCs constituted by the transition metal elements (M) and the chalcogen elements (X) are a large family. M can range from group 4B to group 10 in the periodic table, while X is S, Se, or Te. [41][42][43][44][45][46][47] Figure 1a exhibits the binary TMCs that have already been explored. This variation of composition of elements transfers to a wide range of properties ranging from insulators (e.g., HfS 2 ), [48,49] semiconductors (e.g., MoS 2 , WS 2 ), [50,51] semimetals (e.g., MoTe 2 , TiSe 2 ), [52,53] to metals (e.g., NbSe 2 , VS 2 ). [54][55][56] Furthermore, TMCs can form alloys in the formula such as WSe 2−x S x , with composition-tunable properties. [57][58][59] Unlike semimetallic graphene, semiconducting TMCs usually possess a bandgap. For example, MoS 2 exhibits a bandgap, transitioning from indirect bandgap to direct bandgap when it thins from bulk phase to monolayer (Figure 1b), boosting the photoluminescence (PL) efficiency. [51,[60][61][62] Additionally, inversion symmetry breaking and large spin-orbit interaction, resulting in two energetic degenerate but inequivalent valleys in the band structure of a TMC (Figure 1c), may lead to breakthroughs in valleytronics and spintronics. [63][64][65][66][67][68][69][70] A few TMCs (e.g., NbSe 2 , TaS 2 , VSe 2 ) have shown superconductivity, [71,72] charge density wave [73,74] and Mott transition (transition from metal to nonmetal). [75,76] In addition, some novel TMCs such as Fe 3 GeTe 2 display intrinsic magnetism with gate-tunable Curie points. [66,77] Semimetallic TMCs like WTe 2 show topological structures in the energy band, enabling the study on topological physics. [78,79] The rich intrinsic properties and superior tunability of TMCs hold great promise for all kinds of technologically important applications in electronics, optoelectronics, spintronics, valleytronics, etc. (Figure 1d). [51,[80][81][82][83][84][85][86][87][88][89][90][91] Due to numerous unique properties of 2D TMCs, devices such as transistors, photodetectors (PDs), and photodiodes based on 2D TMCs have been actively pursued. The ultimate destination of the miniaturization of the electronic devices will 2D transition metal chalcogenides (TMCs) have attracted tremendous interest from both the scientific and technological communities due to their variety of properties and superior tunability through layer number, composition, and inter...

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Section: Phasementioning

confidence: 99%

Toward Wafer‐Scale Production of 2D Transition Metal Chalcogenides

Wang

Yang

2021

Adv Elect Materials

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“…[ 122 ] In addition, a contact‐mode AFM tip or a piezo‐controlled tip can also be used to realize mechanical cleaning (Figure 3e,f). [ 119,123,124 ] Based on these methods, researchers can obtain high‐quality graphene for further basic research. However, their use is only limited to laboratory‐scale due to the low throughput.…”

Section: Transfer Of Large‐area Graphene Synthesized By Cvd Techniquementioning

confidence: 99%

Recent Progress in the Transfer of Graphene Films and Nanostructures

Gao

Chen

et al. 2021

Small Methods

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electronics, [9] photonics, [10,11] biosensors, [12,13] etc.One reason that graphene research has developed so fast is the relatively simple and cheap production procedures. Many production approaches have been established, such as top-down approaches, including: mechanical exfoliation, [14] liquid phase exfoliation, [15] reduction of graphene oxide (GO), [16] and electrochemical exfoliation, [17] etc.; as well as bottomup approaches, including: epitaxial growth on SiC, [18] chemical vapor deposition (CVD), [19] etc. Among these approaches, CVD on metal substrates has been widely used to synthesize high quality, large-area graphene (LAG) films. The production of square meters of graphene has been realized, and the state of art devices have been demonstrated. [20] CVD graphene films are ready for applications like transparent conductive films, [20,21] wearable transparent sensors, [22] and ionic/molecular nanofiltration membrane. [23] Despite graphene's extraordinary electronic properties and fast progress in production, zero bandgap of graphene hinders the application of graphene as an electronic transistor. [24] One solution is to engineer graphene into graphene nanostructures (GNs), e.g., graphene nanoribbons (GNRs), [25] graphene nanomeshes (GNMs), [26] graphene quantum dots (GQDs), [27] and other complex shaped nanostructures. [28] Theory predicted that GNRs' bandgap (ΔE(W)) varies as a function of the ribbon width W, ΔE(W) = α W −1 , α is a coefficient with unit [nm eV]. [29][30][31][32] Contrary to the fixed bandgap of a semiconductor-silicon, the bandgap of GNs can be precisely tuned by regulating their edge structure, shape, size, and crystallographic orientation. [26,[33][34][35] Currently, extremely small and dense graphene based-nanoelectronic devices have been achieved by top-down approaches, e.g., electron-beam lithography, [36] block copolymer lithography, [37] and nanosphere lithography. [38] However, top-down patterning of graphene to nanometer scale is challenging without compromising its transport properties. As the pattern density increases, the introduced edge disorders will gradually dominate the electronic properties. Bottom-up approaches, on the other hand, provide an opportunity to synthesize graphene with well-defined edges via solution-mediated or surface-assisted cyclodehydrogenation reactions. [39,40] Since CVD-grown graphene films and surface-assisted grown GNs are generally synthesized on metal foils, their further applications require post-transfer to target substrates. [12,[41][42][43] The one-atom-thick graphene has excellent electronic, optical, thermal, and mechanical properties. Currently, chemical vapor deposition (CVD) graphene has received a great deal of attention because it provides access to large-area and uniform films with high-quality. This allows the fabrication of graphene based-electronics, sensors, photonics, and optoelectronics for practical applications. Zero bandgap, however, limits the application of a graphene film as electronic transistor. The most commonly u...

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“…Conventionally, 2D TMDC materials have been obtained by incorporating Li‐ion diffusion into the bulk TMDC, allowing for chemical exfoliation into a few layered TMDC nanosheets. [ 9,10 ] At the same time, the Li‐incorporated method can cause the phase transformation of 2D TMDC during the intercalation process from the original 2H phase to metallic 1T’ depending on the Li concentration, [ 11 ] meaning that the method may be useful as an easy and mass‐productive way to readily synthesize metallic 2D TMDC materials. However, this method has its own limitations in terms of the fraction yield of the metallic phase.…”

Section: Introductionmentioning

confidence: 99%

Antioxidant Triggered Metallic 1T’ Phase Transformations of Chemically Exfoliated Tungsten Disulfide (WS₂) Nanosheets

Kim

Chae

Jang

et al. 2022

Small

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Developing facile methods for inducing phase transformation between metallic and semiconducting 2D transition metal dichalcogenide (TMDC) materials is crucial toward leveraging their use in cutting‐edge energy devices. Herein, 2H‐to‐1T’ phase transformations in chemically exfoliated Tungsten Disulfide (WS2) nanosheet films, triggered by antioxidants toward highly conductive 2D TMDC electrode materials, are introduced. It is found that antioxidants cause residual LiOx compounds to reduce to Li metal, subsequently inducing 1T’ phase transformations in layered WS2 nanosheets, resulting in significantly enhanced conductivity across the overall films. Both thermoelectric devices and supercapacitors are fabricated utilizing the highly conductive 1T’ phase WS2 nanosheet films as a working electrode, allowing for outstanding performance due to the increased conductivity of the WS2 nanosheet films. The method constitutes a facile approach toward the use of chemically exfoliated 1T’ TMDC nanosheets for highly efficient energy device applications.

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Mechanical removal of surface residues on graphene for TEM characterizations

Cited by 10 publications

References 17 publications

Toward Wafer‐Scale Production of 2D Transition Metal Chalcogenides

Toward Wafer‐Scale Production of 2D Transition Metal Chalcogenides

Recent Progress in the Transfer of Graphene Films and Nanostructures

Antioxidant Triggered Metallic 1T’ Phase Transformations of Chemically Exfoliated Tungsten Disulfide (WS₂) Nanosheets

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Mechanical removal of surface residues on graphene for TEM characterizations

Cited by 10 publications

References 17 publications

Toward Wafer‐Scale Production of 2D Transition Metal Chalcogenides

Toward Wafer‐Scale Production of 2D Transition Metal Chalcogenides

Recent Progress in the Transfer of Graphene Films and Nanostructures

Antioxidant Triggered Metallic 1T’ Phase Transformations of Chemically Exfoliated Tungsten Disulfide (WS2) Nanosheets

Contact Info

Product

Resources

About

Antioxidant Triggered Metallic 1T’ Phase Transformations of Chemically Exfoliated Tungsten Disulfide (WS₂) Nanosheets