Direct visualization of large-area graphene domains and boundaries by optical birefringency

Kim, Dae Woo; Kim, Yun Ho; Jeong, Hyeon Su; Jung, Hee Tae

doi:10.1038/nnano.2011.198

Cited by 224 publications

(139 citation statements)

References 27 publications

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“…Although LC alignment is known to rely on the p-stacking interactions between Gr. and LC molecules 17,18,26 , this effect does not explain the preference of one easy axis over the other two. Further study is needed to understand the origin of LC alignment on Gr.…”

Section: Resultsmentioning

confidence: 83%

“…These methods have several drawbacks, such as the requirement for complicated sample preparation, time delays, and a limited observation area. Recently, Kim et al 17 reported an effective method for visualizing the domains and grain boundaries in Gr. films using the properties of liquid crystal (LC) molecules, which align anisotropically along the Gr.…”

mentioning

confidence: 99%

“…domain orientations. Kim et al 17 suggested that Gr. domains form in alignment with the underlying Cu substrate domains.…”

mentioning

confidence: 99%

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Detection of graphene domains and defects using liquid crystals

et al. 2014

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The direct observation of the domain size and defect distribution in a graphene film is important for the development of electronic applications involving graphene. Here we report a promising method for observing graphene domains grown by chemical vapour deposition. The unavoidable development of crack or pinhole defects during the growth and transfer processes is visualized using a liquid crystal layer. Liquid crystal molecules align anisotropically with respect to the graphene domains and exhibit distinct birefringence properties that can be used to image the graphene domains. This approach is useful for visualizing the crack distributions and their generation process in graphene films under external strain. This type of simple observation method provides an effective route to evaluating the quality and reliability of graphene sheets for use in various electronic devices.

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Section: Resultsmentioning

confidence: 83%

mentioning

confidence: 99%

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Detection of graphene domains and defects using liquid crystals

et al. 2014

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“…Furthermore, STEM can provide histograms of gain sizes and relative grain rotation angles for better understanding of the GBs [209,210]. It is also possible to visualize GBs by optical birefringence of graphene surface covered with nematic liquid crystal [211], by spectroscopic Raman imaging of the defect-activated D mode [78,212], and by infrared nanoimaging technique [213]. …”

Section: Disorders In Graphene Structurementioning

confidence: 99%

Structure of graphene and its disorders: a review

Gao

Lee

et al. 2018

Science and Technology of Advanced Materials

533

187

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Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.

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“…However, it is possible to use auxiliary agents that have characteristic interactions with graphene grains or GBs to aid in optical imaging. For example, Kim et al developed a simple method to visualize graphene grains and GBs by imaging the birefringence of a graphene surface covered with nematic liquid crystals, taking advantage of the orientation of the liquid crystals with the underlying graphene lattice (thus mapping the graphene grains and GBs to those of the corresponding liquid crystal domains) 96 . Using optical microscopy, one can also enhance the contrast of grains and make GBs more visible by taking advantage of the more effective oxidation of substrate (Cu) in the region exposed or under GBs (which can be further functionalized to facilitate oxidation) 97,98 .…”

Section: Optical Imaging and Characterizationmentioning

confidence: 99%

Polycrystalline graphene and other two-dimensional materials

2014

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Graphene, a single atomic layer of graphitic carbon, has attracted intense attention due to its extraordinary properties that make it a suitable material for a wide range of technological applications. Large-area graphene films, which are necessary for industrial applications, are typically polycrystalline, that is, composed of single-crystalline grains of varying orientation joined by grain boundaries. Here, we present a review of the large body of research reported in the past few years on polycrystalline graphene. We discuss its growth and formation, the microscopic structure of grain boundaries and their relations to other types of topological defects such as dislocations. The review further covers electronic transport, optical and mechanical properties pertaining to the characterizations of grain boundaries, and applications of polycrystalline graphene. We also discuss research, still in its infancy, performed on other 2D materials such as transition metal dichalcogenides, and offer perspectives for future directions of research.Comment: review article; part of focus issue "Graphene applications

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Direct visualization of large-area graphene domains and boundaries by optical birefringency

Cited by 224 publications

References 27 publications

Detection of graphene domains and defects using liquid crystals

Detection of graphene domains and defects using liquid crystals

Structure of graphene and its disorders: a review

Polycrystalline graphene and other two-dimensional materials

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