Localization of lattice dynamics in low-angle twisted bilayer graphene

Gadelha, Andreij C.; Ohlberg, Douglas A. A.; Rabelo, Cassiano; Neto, Eliel G. S.; Vasconcelos, Thiago L.; Campos, João Luiz; Lemos, Jessica S.; Ornelas, Vinícius; Miranda, Daniel Andrade; Nadas, Rafael; Santana, Fabiano C.; Watanabe, Kenji; Taniguchi, Takashi; Troeye, Benoît Van; Lamparski, Michael; Meunier, Vincent; Nguyễn, Việt Hùng; Paszko, Dawid; Charlier, Jean‐Christophe; Campos, Leonardo; Cançado, Luiz Gustavo; Medeiros‐Ribeiro, G.; Jório, Ado

doi:10.1038/s41586-021-03252-5

Cited by 179 publications

(188 citation statements)

References 45 publications

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“…These samples were characterized by Raman spectroscopy (supplementary Fig. 2 ), Tip Enhanced Raman Spectroscopy microscopy 21 , and Ultra High Vacuum-STM (supplementary Fig. 3 ), to independently verify the bilayer locations and confirm the observed moiré superlattices that arise in TBG systems.…”

Section: Resultsmentioning

confidence: 99%

“…The twisted bilayer samples analyzed were prepared using a technique we have developed that is a variation of conventional, dry transfer, tear-and-stack methods 21 , 31 . Unlike other procedures, which either completely encapsulate graphene bilayers within a top and bottom layer of h-BN flakes or a bottom layer of h-BN flake and a top layer of polymer that often requires removal in subsequent solvent soaks and sample bakes, our dry transfer procedure fabricates simple, extremely clean, and unencapsulated TBGs free of polymers that can introduce undesired contaminants.…”

Section: Methodsmentioning

confidence: 99%

“…The procedure relies on a special stamp design consisting of a truncated, polymer pyramid fabricated on a handle substrate that is not only capable of performing tear-and-stack operations on the initial graphene but also allows subsequent detachment of the bilayer onto a variety of support substrates. The substrate supports included simple glass coverslips with and without h-BN coating layers that were used for tip-enhanced Raman spectroscopy (TERS) analysis (published elsewhere 21 ), mica coupons coated with atomically flat gold for STM analysis, and silicon coupons coated with a 275 nm oxide. After transfer to a respective substrate, a WITec Alpha 300 SAR confocal Raman Microscope was used for Raman spectroscopy and spatial mapping.…”

Section: Methodsmentioning

confidence: 99%

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The limits of near field immersion microwave microscopy evaluated by imaging bilayer graphene moiré patterns

et al. 2021

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Near field scanning Microwave Impedance Microscopy can resolve structures as small as 1 nm using radiation with wavelengths of 0.1 m. Combining liquid immersion microscopy concepts with exquisite force control exerted on nanoscale water menisci, concentration of electromagnetic fields in nanometer-size regions was achieved. As a test material we use twisted bilayer graphene, because it provides a sample where the modulation of the moiré superstructure pattern can be systematically tuned from Ångstroms up to tens of nanometers. Here we demonstrate that a probe-to-pattern resolution of 108 can be obtained by analyzing and adjusting the tip-sample distance influence on the dynamics of water meniscus formation and stability.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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The limits of near field immersion microwave microscopy evaluated by imaging bilayer graphene moiré patterns

et al. 2021

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“…[233] Similarly, because the FWHM of the TBG Raman G band from the AA-stacking region is the largest, while that from the AB-/BA-stacking is the smallest, these bands can be used as characteristics for constructing the image of the moiré superlattice (Figure 8e). [231] Visualization of the TBG moiré superlattice can also be performed by using s-SNOM to map the polaritons. [236] When the plasmonic polaritons in TBG are excited through illumination of the AFM tip, they propagate radially outward from the tip, and are be reflected back by the domain walls (SP stacking).…”

Section: Optical Inspection Of Vdw Integration Of 2d Materialsmentioning

confidence: 99%

Section: Optical Inspection Of Vdw Integration Of 2d Materialsmentioning

confidence: 99%

Optical Inspection of 2D Materials: From Mechanical Exfoliation to Wafer‐Scale Growth and Beyond

et al. 2021

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Optical inspection is a rapid and non-destructive method for characterizing the properties of two-dimensional (2D) materials. With the aid of optical inspection, in situ and scalable monitoring of the properties of 2D materials can be implemented industrially to advance the development and progress of 2D material-based devices toward mass production. This review discusses the optical inspection techniques that are available to characterize various 2D materials, including graphene, transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), group-III monochalcogenides, black phosphorus (BP), and group-IV monochalcogenides. First, the authors provide an introduction to these 2D materials and the processes commonly used for their fabrication. Then they review several of the important structural properties of 2D materials, and discuss how to characterize them using appropriate optical inspection tools. The authors also describe the challenges and opportunities faced when applying optical inspection to recently developed 2D materials, from mechanically exfoliated to wafer-scale-grown 2D materials. Most importantly, the authors summarize the techniques available for largely and precisely enhancing the optical signals from 2D materials. This comprehensive review of the current status and perspective of future trends for optical inspection of the structural properties of 2D materials will facilitate the development of next-generation 2D material-based devices.

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Investigation of Doping Effects on the Local Electrochemical Activity of Transition Metal Dichalcogenides 2D Materials

Silva,

Kim,

de Oliveira

et al. 2024

Adv Funct Materials

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Finding strategies to enhance catalysts’ electrochemical activity is based on controlling the material design. Bidimensional materials (2DM) such as MoS2 are explored as catalysts for the hydrogen evolution reaction (HER). A comprehensive study of the effects of doping 2D materials with transition metals based on theoretical predictions in tandem with experimental investigation correlates the doping type to the changes in the electronic and electrochemical activity. Localized electrochemical maps obtained by scanning electrochemical cell microscopy (SECCM) reveal that Ti‐doping induces a heterogeneous increase in 2H‐MoS2 basal plane electrochemical activity, while Ni‐doping induces a homogeneous decrease. Additionally, Kelvin probe microscopy provides insight into Ti‐doping, showcasing a decline in the 2H‐MoS2 work function, therefore confirming the predictions from density functional theory simulations. In essence, the findings underscore the potential of transition metal coordination on the 2H‐MoS2 surface as an attractive method for locally doping 2D materials with minimal damage to the crystalline lattice, consequently enhancing the electrochemical activity on the material's basal plane.

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Localization of lattice dynamics in low-angle twisted bilayer graphene

Cited by 179 publications

References 45 publications

The limits of near field immersion microwave microscopy evaluated by imaging bilayer graphene moiré patterns

The limits of near field immersion microwave microscopy evaluated by imaging bilayer graphene moiré patterns

Optical Inspection of 2D Materials: From Mechanical Exfoliation to Wafer‐Scale Growth and Beyond

Investigation of Doping Effects on the Local Electrochemical Activity of Transition Metal Dichalcogenides 2D Materials

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