Convergent beam electron holography for analysis of van der Waals heterostructures

Abstract

Van der Waals heterostructures, which explore the synergetic properties of two-dimensional (2D) materials when assembled into three-dimensional stacks, have already brought to life a number of exciting new phenomena and novel electronic devices. Still, the interaction between the layers in such assembly, possible surface reconstruction, intrinsic and extrinsic defects are very difficult to characterise by any method, because of the single-atomic nature of the crystals involved. Here we present a convergent beam electron holographic technique which allows imaging of the stacking order in such heterostructures. Based on the interference of electron waves scattered on different crystals in the stack, this approach allows one to reconstruct the relative rotation, stretching, out-of-plane corrugation of the layers with atomic precision. Being holographic in nature, our approach allows extraction of quantitative information about the three-dimensional structure of the typical defects from a single image covering thousands of square nanometres. Furthermore, qualitative information about the defects in the stack can be extracted from the convergent diffraction patterns even without reconstruction - simply by comparing the patterns in different diffraction spots. We expect that convergent beam electron holography will be widely used to study the properties of van der Waals heterostructures.

References in corpus (11)

• Van der Waals heterostructures
• 2D materials and van der Waals heterostructures
• Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices
• On the roughness of single- and bi-layer graphene membranes
• Electronic Properties of Graphene Encapsulated with Different Two-Dimensional Atomic Crystals
• Solution to the twin image problem in holography
• Control of Radiation Damage in MoS2 by Graphene Encapsulation
• Practical algorithms for simulation and reconstruction of digital in-line holograms
• The pristine atomic structure of MoS2 monolayer protected from electron radiation damage by graphene
• Graphene as a transparent conductive support for studying biological molecules by transmission electron microscopy
• Unraveling the 3D atomic structure of a suspended graphene/hBN van der Waals heterostructure

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• Convergent and divergent beam electron holography and reconstruction of adsorbates on free-standing two-dimensional crystals
• Convergent beam electron diffraction of multilayer van der Waals structures
• Stacking control in graphene-based materials: a promising way for fascinating physical properties
• Holographic reconstruction of the interlayer distance of bilayer two-dimensional crystal samples from their convergent beam electron diffraction patterns
• Imaging defects in two-dimensional crystals by convergent beam electron diffraction
• Considerations for extracting moiré-level strain from dark field intensities in transmission electron microscopy
• Potentials of individual atoms by convergent beam electron diffraction
• Dynamics of single Au nanoparticles on graphene simultaneously in real- and diffraction space by time-series convergent beam electron diffraction
• Holographic convergent electron beam diffraction (CBED) imaging of two-dimensional crystals
• Untangling 3D atomic reconstruction in twisted bilayer 2D crystals via dark field transmission electron microscopy