Session 6-3

Abstract

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM) is an electron microscopy technique that captures a series of convergent beam electron diffraction (CBED)/ patterns measured at each probe position using a pixelated detector. The incident electron beam is rastered over the sample in a two-dimensional (2D) pattern and a corresponding diffraction pattern (2D) is recorded for each position producing a “4D” dataset. These 4D datasets contain a wealth of information because they consist of tens of thousands of diffraction patterns sampled from multiple structural regions that are useful for determining local strain and defects, orientation maps at the nanometer scale using automatic crystal orientation matching (ACOM), the change in lattice parameters as a function of environmental stimuli such as temperature, and other sample-dependent properties. The large volumes of data are computationally challenging, requiring complex analysis that includes custom-built and open-source codes such as py4DSTEM for post-processing. Overcoming these challenges paves the way for exploring the structure of materials at enhanced resolutions for a wide array of applications.