Basic Principles and Application of Electron Channeling in a Scanning Electron Microscope for Dislocation Analysis

Dislocations are extended defects within crystalline solids that often influence the mechanical, electrical, magnetic and optical properties of the material. Establishing more quantitative relationships between dislocations and material properties relies on effective microscopy or spectroscopy methods that can resolve both dislocation type and position within the solid. Diffraction has historically been an effective mechanism in electron microscopy for creating image contrast necessary to locate and identify various dislocations within materials. Transmission electron microscopy (TEM) has long been the most conventional method employing diffraction contrast for dislocation analysis. However, scanning electron microscopes (SEM) can also access diffraction contrast through the phenomenon of electron channeling. This article highlights recent research progress in the imaging and identification of dislocations using SEM-based electron channeling. A brief introduction to electron channeling is provided and various example microscopy images of dislocations are presented. Practical details are provided on how to access electron channeling in a conventional SEM, optimizing channeling contrast, and intepreting the nature of channeling contrast features.