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Decoding the structure of interfaces and impurities in 2D materials by photoelectron holography
摘要： The properties of atomically thin materials essentially depend on their structures, including impurities, defects and interfaces with underlying substrates. Thus, the detailed structural information is relevant for creation of 2D materials with desired properties. Here, we explore the capabilities of photoelectron diffraction and holography for structural analysis of atomically thin layers using as examples such systems as h-BN, graphene, and modified graphene with boron impurities. We show that for planar 2D crystals with commensurate interface to the substrate, it is possible to visualize the interface and impurities with high spatial resolution, and to distinguish possible non-equivalent structural units. Our approach applied to B-doped graphene on Ni(1 1 1) and Co(0 0 0 1) surfaces has allowed to reveal asymmetry of boron concentrations in the two carbon sublattices and established its dependence on the applied synthesis procedure and chosen substrate. The obtained results suggest that such approach can be widely applied for studies of various 2D systems, where the structures of interfaces and defects are of remarkable importance.
关键词： doping,structure,photoelectron diffraction,graphene,hexagonal boron nitride,photoelectron holography
更新于2025-09-19 17:13:59
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Tunable reflected group delay from the graphene/hBN heterostructure at infrared frequencies
摘要： In this paper, we theoretically investigated the re?ected group delay from the graphene/hexagonal boron nitride (hBN) heterostructure in the infrared band. Since the signi?cant Lorentz resonance characteristic of the dielectric constant of hBN in the bands of near 7.28 μm and 12.72 μm, the new graphene/hBN heterostructure is used to realize ?exible switching of re?ected group delay by the Lorentz resonance mechanism. It is shown that the re?ected group delay can be e?ectively enhanced by tuning the Fermi energy or the number of graphene layers. Moreover, the re?ected group delay can be tuned positive or negative depending on the hBN thickness or incident angle. These results will be useful for design of graphene-based optical delay devices in the infrared band.
关键词： Graphene,Hexagonal boron nitride (hBN),Group delay,Infrared band
更新于2025-09-12 10:27:22
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Impacts of in-plane strain on commensurate graphene/hexagonal boron nitride superlattices
摘要： Due to atomically thin structure, graphene/hexagonal boron nitride (G/hBN) heterostructures are intensively sensitive to the external mechanical forces and deformations being applied to their lattice structure. In particular, strain can lead to the modification of the electronic properties of G/hBN. Furthermore, moiré structures driven by misalignment of graphene and hBN layers introduce new features to the electronic behavior of G/hBN. Utilizing ab initio calculation, we study the strain-induced modification of the electronic properties of diverse stacking faults of G/hBN when applying in-plane strain on both layers, simultaneously. We observe that the interplay of few percent magnitude in-plane strain and moiré pattern in the experimentally applicable systems leads to considerable valley drifts, band gap modulation and enhancement of the substrate-induced Fermi velocity renormalization. Furthermore, we find that regardless of the strain alignment, the zigzag direction becomes more efficient for electronic transport, when applying in-plane non-equibiaxial strains.
关键词： strain,graphene/hexagonal boron nitride,moiré pattern,electronic properties
更新于2025-09-10 09:29:36