Recording and Using 4D-STEM Datasets in Materials Science

Traditional scanning transmission electron microscopy (STEM) detectors are monolithic and integrate a subset of the transmitted electron beam signal scattered from each electron probe position, shown schematically in Figure 1. These convergent beam electron diffraction patterns (CBED) are extremely rich in information, containing localized information on sample structure [1], composition [2], phonon spectra [3], three-dimensional defect crystallography [4] and more. Many new imaging modes become possible if the full CBED pattern is recorded at many probe positions with millisecond dwell times. Such a four-dimensional dataset would be comprised of a 2D CBED pattern at each point in a 2D STEM raster, hence the name 4D-STEM.