METHOD FOR AUTOMATICALLY ALIGNING A SCANNING TRANSMISSION ELECTRON MICROSCOPE FOR PRECESSION ELECTRON DIFFRACTION DATA MAPPING

摘要

A method for automatically aligning a scanning tunneling electron microscope (STEM) for acquiring precession electron diffraction (PED) mapping data includes the generation of an incident electron beam aligned with a STEM optic axis and focused on a sample region. A non-inclined signal is acquired of the spatial distribution from the sample region, by scanning the aligned incident beam across multiple discrete locations and acquiring a signal associated with each location. The method can further include the inclination of the incident electron beam to a fixed inclination angle relative to the optic axis and then acquiring an inclined signal spatial distribution from the sample region by scanning the inclined incident beam across the multiple discrete locations while applying a cyclic azimuthal scanning protocol to the inclined beam and acquiring a signal associated with each location. An azimuthal spatial alignment correction is determined by comparing the non-inclined and inclined signal spatial distributions.