Scanning Precession Electron Diffraction (SPED) Workshop

This talk will introduce the core principles of the technique, explain why precession improves data quality, and show how combining PED with beam scanning enables automated, nanoscale mapping of crystal orientation, phase, and strain in the TEM, laying the groundwork for the application sessions that follow. Whether you’re new to electron diffraction or looking to expand your TEM toolkit, this session will give you a practical foundation for understanding scanning PED and what it can do for your research.

A presentation of how scanned precessed electron diffraction can map different material properties: short-range ordering, internal apparent electrical fields, relative strain in single-crystal layers, crystallographic orientation in and out of the sample plane in polycrystalline samples, and crystallographic phase distribution.

Ferroelectric hafnium zirconium oxide (HZO) thin films are under development for nonvolatile memory and logic devices, but typical processing produces small grains of several phases with very similar lattice parameters, including the ferroelectric orthorhombic phase (space group 29) and nonferroelectric monoclinic, tetragonal, and orthorhombic phases. In this talk, I will describe how we used scanning precession electron diffraction (SPED) and automated template matching to map the phase and orientation of grains in 10 nm thick HZO films. We compared the NanoMEGAS ASTAR software with the open source py4DSTEM package, where we added precession to the diffraction simulations. Both codes found that the ferroelectric orthorhombic and monoclinic phases dominate, though the phase fractions differed, which we attribute mainly to their different matching cost functions. I will also discuss how dynamical diffraction simulations and tilt series measurements can make these phase measurements more reliable in our new open source quantEM code.