Probing Bilayer Grain Boundaries in Large‐Area Graphene with Tip‐Enhanced Raman Spectroscopy

Park, Kyoung Duck; Raschke, Markus B.; Atkin, Joanna M.; Lee, Young Hee; Jeong, Mun Seok

doi:10.1002/adma.201603601

Cited by 45 publications

(43 citation statements)

References 32 publications

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“…Confocal Raman spectroscopy gives spatially resolved information about the vibrational spectrum, so-called Raman images. A state of the art Raman imaging system can achieve a spatial resolution of B300 nm if we do not use some special techniques, such as near-field Raman technique, tip enhanced Raman scattering (TERS), 311 or microspheres (or lens). With the development of high-performance charge-coupled devices (CCDs) and also the optimization of optical items, the integration time required for obtaining a smooth Raman spectrum can be as short as milliseconds, which greatly minimizes the time to acquire Raman imaging.…”

Section: Raman Images Of Graphene Flakesmentioning

confidence: 99%

Raman spectroscopy of graphene-based materials and its applications in related devices

et al. 2018

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Graphene-based materials exhibit remarkable electronic, optical, and mechanical properties, which has resulted in both high scientific interest and huge potential for a variety of applications. Furthermore, the family of graphene-based materials is growing because of developments in preparation methods. Raman spectroscopy is a versatile tool to identify and characterize the chemical and physical properties of these materials, both at the laboratory and mass-production scale. This technique is so important that most of the papers published concerning these materials contain at least one Raman spectrum. Thus, here, we systematically review the developments in Raman spectroscopy of graphene-based materials from both fundamental research and practical (i.e., device applications) perspectives. We describe the essential Raman scattering processes of the entire first- and second-order modes in intrinsic graphene. Furthermore, the shear, layer-breathing, G and 2D modes of multilayer graphene with different stacking orders are discussed. Techniques to determine the number of graphene layers, to probe resonance Raman spectra of monolayer and multilayer graphenes and to obtain Raman images of graphene-based materials are also presented. The extensive capabilities of Raman spectroscopy for the investigation of the fundamental properties of graphene under external perturbations are described, which have also been extended to other graphene-based materials, such as graphene quantum dots, carbon dots, graphene oxide, nanoribbons, chemical vapor deposition-grown and SiC epitaxially grown graphene flakes, composites, and graphene-based van der Waals heterostructures. These fundamental properties have been used to probe the states, effects, and mechanisms of graphene materials present in the related heterostructures and devices. We hope that this review will be beneficial in all the aspects of graphene investigations, from basic research to material synthesis and device applications.

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Section: Raman Images Of Graphene Flakesmentioning

confidence: 99%

Raman spectroscopy of graphene-based materials and its applications in related devices

et al. 2018

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“…Tip-enhanced Raman spectroscopy (TERS) can simultaneously provide the high spatial resolution and chemical sensitivity needed for materials and device characterisation at the nanoscale through the highly confined enhanced electromagnetic field generated within a plasmonic nano-cavity. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] It has recently been demonstrated that TERS systems based on a scanning tunnelling microscope (STM) can obtain impressive images and information with subnanometre resolution, [10][11][12] but these systems are restricted to special extreme environments (e.g. ultra-high vacuum and low temperature) that are not suitable to study the asfabricated electrical and mechanical properties of devices.…”

Section: Introductionmentioning

confidence: 99%

Visualization of subnanometric phonon modes in a plasmonic nano-cavity via ambient tip-enhanced Raman spectroscopy

et al. 2019

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Phonons provide information on the physicochemical properties of a crystalline lattice from the material's vibrational spectrum. Optical phonons, in particular, can be probed at both micrometre and nanometre scales using light-based techniques, such as, micro-Raman and tip-enhanced Raman spectroscopy (TERS), respectively. Selection rules, however, govern the accessibility of the phonons and, hence, the information that can be extracted about the sample. Herein, we simultaneously observe both allowed and forbidden optical phonon modes of defect-free areas in monolayer graphene to study nanometre scale strain variations and plasmonic activation of the Raman peaks, respectively, using our home-built TERS system in ambient. Through TERS imaging, strain variations and nanometre-sized domains down to 5 nm were visualised with a spatial resolution of 0.7 nm. Moreover, such subnanometric confinement was found to activate not only the D and D' forbidden phonon modes but also their D + D' combination mode. With our TERS in ambient system, the full phonon characterisation of defect-free graphene and other 2D nanomaterials is now possible, which will be useful for subnanometre strain analysis and exploring the inherent properties of defect-free materials.

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“…Raman intensity changes in CVD-grown monolayer graphene are mainly related to defects, (folded) wrinkles, and overlaps of the graphene layers. Wrinkles are usually formed during the post-growth cooling of graphene on a Cu substrate owing to the difference in thermal expansion coefficients between graphene and Cu 10 , 26 . Polycrystalline graphene consists of single-crystal domains with different crystallographic orientations.…”

Section: Resultsmentioning

confidence: 99%

“…Polycrystalline graphene consists of single-crystal domains with different crystallographic orientations. The individual domains are merged together with the formation of defects, wrinkles, and/or overlapped structures at the domain boundaries 10 , 26 , 27 . Moreover, defective or atomically smooth connections can be formed at the domain boundaries with flat interfaces 27 .…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, for the multilayer graphene boundary and the folded wrinkle, the integrated intensity of the G peak ( I G ) usually increases owing to an increase in the number of graphene layers compared to the surrounding monolayer region 10 , 29 , 30 . The integrated intensity of the 2D peak ( I 2D ) decreases at the wrinkle (not folded) owing to a structural curvature effect, whereas the integrated intensities of the G and D peaks do not change at the wrinkle 26 . At the overlapped bilayer domain boundary, I 2D depends on the twisted stacking angle between the misoriented monolayer graphene domains 26 , 31 .…”

Section: Resultsmentioning

confidence: 99%

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Spatially resolved Raman spectroscopy of defects, strains, and strain fluctuations in domain structures of monolayer graphene

Lee

Mas’ud

Kim

et al. 2017

Sci Rep

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We report spatially resolved Raman scattering results of polycrystalline monolayer graphene films to study the effects of defects, strains, and strain fluctuations on the electrical performance of graphene. Two-dimensional Raman images of the integrated intensities of the G and D peaks (I G and I D) were used to identify the graphene domain boundaries. The domain boundaries were also identified using Raman images of I D/I G and I 2D/I G ratios and 2D spectral widths. Interestingly, the I D maps showed that the defects within individual domains significantly increased for the graphene with large domain size. The correlation analysis between the G and 2D peak energies showed that biaxial tensile strain was more developed in the graphene with large domain size than in the graphene with small domain size. Furthermore, spatial variations in the spectral widths of the 2D peaks over the graphene layer showed that strain fluctuations were more pronounced in the graphene with large domain size. It was observed that the mobility (sheet resistance) was decreased (increased) for the graphene with large domain size. The degradation of the electrical transport properties of the graphene with large domain size is mainly due to the defects, tensile strains, and local strain fluctuations within the individual domains.

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Probing Bilayer Grain Boundaries in Large‐Area Graphene with Tip‐Enhanced Raman Spectroscopy

Cited by 45 publications

References 32 publications

Raman spectroscopy of graphene-based materials and its applications in related devices

Raman spectroscopy of graphene-based materials and its applications in related devices

Visualization of subnanometric phonon modes in a plasmonic nano-cavity via ambient tip-enhanced Raman spectroscopy

Spatially resolved Raman spectroscopy of defects, strains, and strain fluctuations in domain structures of monolayer graphene

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