Diffraction-Based Characterization of Polycrystalline Two-Dimensional Materials—A WSe₂ Case Study

Application relevant materials are usually polycrystalline, and one of the major challenges in structural analysis resides in accurately identifying the grain boundary orientation and size distribution over a wide field of view with enough spatial resolution to capture tens-of-nanometer sized domains. Four-dimensional scanning transmission electron microscopy (4D-STEM) now enables the fast collection of nano-beam electron diffraction patterns on a two-dimensional array of spatial positions in which various computational analyses can reveal structural variations on a pixel-by-pixel basis over different scales while reducing knock-on damage in samples which have been traditionally very challenging to characterize. In this presentation, I will showcase our advancements in the field of transmission electron microscopy and nanoscience with an emphasis on understanding effects of strain and defects in low-dimensional materials including transmission electron microscopy-based automated orientation mapping, which has significant follow-on impact for electron scattering based nanoscale structure characterization in application relevant 2D materials such as WSe₂.