Dark-field transmission electron microscopy and the Debye-Waller factor of graphene

Shevitski, Brian; Mecklenburg, Matthew; Hubbard, William A.; White, Edward M.; Dawson, B.; Lodge, Michael S.; Ishigami, Masa; Regan, B. C.

doi:10.1103/physrevb.87.045417

Cited by 40 publications

(35 citation statements)

References 36 publications

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“…In regions of the sample which contained a large fraction of AB stacking as indicated by 2D band deconvolution, we observed a strong “oTO” band (≈1750 cm −1 , the out‐of‐plane transverse optical phonon) and suppressed “iTALO” band (≈1860 cm −1 , combination of the in‐plane transverse acoustic and the longitudinal optical phonons) in the second order region of the spectrum whilst in regions of the sample which were mostly turbostratic, the attenuated “oTO” band and stronger “iTALO” band further confirm the turbostratic stacking (see Figure S14 in the Supporting Information) . We also exfoliated the SG2800 sample using the “scotch tape” method to prepare samples with a few layers for observing the stacking order between the graphene layers using dark‐field TEM analysis (Figure S19, Supporting Information) . Similar to the results of the Raman analysis, some regions displayed turbostratic stacking while other regions displayed AB stacking.…”

Section: Measured Interlayer Spacing Of Graphene Layers In Each Samplsupporting

confidence: 58%

Ultrastiff, Strong, and Highly Thermally Conductive Crystalline Graphitic Films with Mixed Stacking Order

et al. 2019

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A macroscopic film (2.5 cm × 2.5 cm) made by layer‐by‐layer assembly of 100 single‐layer polycrystalline graphene films is reported. The graphene layers are transferred and stacked one by one using a wet process that leads to layer defects and interstitial contamination. Heat‐treatment of the sample up to 2800 °C results in the removal of interstitial contaminants and the healing of graphene layer defects. The resulting stacked graphene sample is a freestanding film with near‐perfect in‐plane crystallinity but a mixed stacking order through the thickness, which separates it from all existing carbon materials. Macroscale tensile tests yields maximum values of 62 GPa for the Young's modulus and 0.70 GPa for the fracture strength, significantly higher than has been reported for any other macroscale carbon films; microscale tensile tests yield maximum values of 290 GPa for the Young's modulus and 5.8 GPa for the fracture strength. The measured in‐plane thermal conductivity is exceptionally high, 2292 ± 159 W m−1 K−1 while in‐plane electrical conductivity is 2.2 × 105 S m−1. The high performance of these films is attributed to the combination of the high in‐plane crystalline order and unique stacking configuration through the thickness.

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Section: Measured Interlayer Spacing Of Graphene Layers In Each Samplsupporting

confidence: 58%

Ultrastiff, Strong, and Highly Thermally Conductive Crystalline Graphitic Films with Mixed Stacking Order

et al. 2019

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“…22 Figure 1(b) shows a typical TEM image of the mono-layer graphene sample recorded at room temperature, illustrating the overall sample cleanliness with contamination free areas of the order of a few hundred nm 2 . Using kinematical scattering theory, Shevitski and coworkers have derived 14 an analytical expression for the number of electrons scattered into a reflection (N peak ) at a scattering vector Dk as…”

Section: Resultsmentioning

confidence: 99%

“…13,14 Knowledge of the DWF in low dimensional materials, such as mono-layer graphene, not only provides information about the nature of long range crystalline order but also aids our understanding of scattering processes in these materials which is essential to any quantitative description of image formation in transmission electron microscopy.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of atomic vibrations in mono-layer graphene

Allen

Liberti

Kim

et al. 2015

Journal of Applied Physics

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We have measured the mean square amplitude of both in-and out-of-plane lattice vibrations for mono-layer graphene at temperatures ranging from $100 K to 1300 K. The amplitude of lattice vibrations was calculated from data extracted from selected area electron diffraction patterns recorded across a known temperature range with over 80 diffraction peaks measured per diffraction pattern. Using an analytical Debye model, we have also determined values for the maximum phonon wavelength that can be supported by a mono-layer graphene crystal and the magnitude of quantum mechanical zero point vibrations. For in-plane phonons, the quantum mechanical zero point contribution dominates the measured atomic displacement at room temperature, whereas for out-of-plane modes, thermally populated phonons must be considered. We find a value for the maximum phonon wavelength sampled that is several orders of magnitudes smaller than the physical crystallite size. V C 2015 AIP Publishing LLC. [http://dx

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“…To illustrate the essence of electron diffraction pattern evolution with thickness of atomically thin ReSe2, an analytic kinematical diffraction theory approximation has been developed in this study, which is usually applicable to ultra-thin specimens and light-element atoms [38,41]. In the classic description of electron diffraction processes, electrons are scattered by specimen's electrostatic potential, and according to the first Born approximation, amplitude of diffracted beam is proportional to the Fourier transform of the corresponding specimen's potential.…”

Section: Theoretical Basismentioning

confidence: 99%

Direct identification of monolayer rhenium diselenide by an individual diffraction pattern

Fei

Wang

et al. 2017

Nano Res.

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In the current extensive studies of layered two-dimensional (2D) materials, compared to the hexagonal ones, like graphene, hBN and MoS2, low symmetry 2D materials have shown great potential for applications in anisotropic devices. Rhenium diselenide (ReSe2) has the bulk space group P1 � and belongs to triclinic crystal system with a deformed cadmium iodide type structure. Here we propose an electron diffraction based method to distinguish monolayer ReSe2 membrane from multilayer ReSe2, and its two different vertical orientations, our method could also be applicable to other low symmetry crystal systems, including both triclinic and monoclinic lattices, as long as their third unit-cell basis vectors are not perpendicular to their basal planes. Our experimental results are well explained by kinematical electron diffraction theory and corresponding simulations. The generalization of our method to other 2D materials, like graphene, is also discussed.Address correspondence to Chuanhong Jin, chhjin@zju.edu.cn Moreover, ReS2 and ReSe2 share similar crystal structures, they both have a distorted octahedral 1T structure and belong to triclinic crystal system, and Re atoms form zigzag chains in the basal plane, arising from the Peierls distortion. Therefore, ReSe2 and ReS2 flakes have both in-plane and out-of-plane anisotropy, and recently there have been numbers of applications based on their anisotropic properties [12][13][14][15][16][17].When materials are thinned down to atomically thin membranes, thickness begins to play an important role in tailoring their properties, and vice versa, there are a variety of techniques to determine their thicknesses, ranging from image contrast of reflected light microscopy [18][19][20][21][22][23][24], second harmonic microscopy [25][26][27][28], intuitive atomic force microscopy and cross-sectional imaging to Raman and photoluminescence spectroscopy [29][30][31][32]. In the field of electron microscopy, there are miscellaneous methods to identify thickness as well, which include peak shift in plasmon spectroscopy [33,34], direct high-resolution transmission electron microscopy (HRTEM) imaging combined with simulations [35] and linearity in annular dark field scanning transmission electron microscope (ADF-STEM) signals [36,37]. Apart from the above methods, electron diffraction analysis [34,[38][39][40][41][42][43] has also been demonstrated as an efficient tool to determine thickness in 2D materials, since it could be conducted on any commercial uncorrected TEM conveniently with negligible beam damages on a large area of pristine crystalline samples. Furthermore, diffraction based methods usually involve a series of sample tilting or use the relative ratio of the chosen diffraction spots, and some researchers noticed the intensity mismatch in a pair of crystallographically equivalent diffraction spots (Friedel pair) [41,44,45], here we demonstrate a method of identifying monolayer ReSe2 by the centrosymmetry with a single diffraction pattern.

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Dark-field transmission electron microscopy and the Debye-Waller factor of graphene

Cited by 40 publications

References 36 publications

Ultrastiff, Strong, and Highly Thermally Conductive Crystalline Graphitic Films with Mixed Stacking Order

Ultrastiff, Strong, and Highly Thermally Conductive Crystalline Graphitic Films with Mixed Stacking Order

Temperature dependence of atomic vibrations in mono-layer graphene

Direct identification of monolayer rhenium diselenide by an individual diffraction pattern

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