Development of a Pixelated STEM-in-SEM detector for microstructural feature characterization

The Scanning Transmission Electron Microscopy in a Scanning Electron Microscope (STEM-in-SEM) approach proposed in this work addresses the possibilities and limitations of a prototype developed for microstructural characterization in thin foils. The developed detector comprises a digital micromirror device (DMD) that can generate user-defined apertures for electron microscopy. As such, TEM-like characterizations are possible while minimizing the presence of artifacts that sometimes hinder analyses. In addition, the developed detector benefits from an On-Axis Transmission Kikuchi Diffraction (On-Axis TKD) geometry, allowing relatively fast diffraction pattern acquisition with a high signal-to-noise ratio. The experimental results demonstrate both the ability to obtain diffraction patterns and to image microstructural defects — including diffraction contrast to characterize dislocations — under adjustable bright-field and dark-field conditions. The proposed Pixelated STEM-in-SEM technique is part of a broader framework aimed at transferring TEM techniques to the Scanning Electron Microscope (SEM).