Convergent beam electron holography for analysis of van der Waals heterostructures

Significance Assembling 2D materials into vertically stacked heterostructures allows an unprecedented control over their properties. The interaction between the individual crystals plays the crucial role here; thus, the information about the local atomic stacking is of great importance. Still, there are no techniques which would allow investigation of the stacking between such crystals with any reasonable throughput. We present the use of convergent beam electron diffraction (CBED) to investigate the quality of the interface in such heterostructures. We demonstrate that defects such as misorientation, strain, ripples, and others can be visualized, and quantitative information about such structures can be easily extracted. Furthermore, CBED images can be treated as holograms; thus their reconstruction gives 3D profiles of the heterostructures over a large area.