Electron Channeling Contrast in the SEM

Abstract

Electron channeling is an effect of the interaction of energetic electrons with crystalline materials which can be used to detect the crystal-lographic properties of a sample in an SEM image. With a suitable sample and proper attention to the electron optical requirements for the detection of electron channeling contrast, it is possible in any SEM to form images of the crystallographic microstructure of a sample, including high-and low-angle grain boundaries, and it is also possible to obtain electron channeling patterns, which provide direct information on orientation relative to the incident beam, from large single crystals. With special scanning systems, electron channeling patterns can be formed from selected areas with dimensions as small as 1–5 µm in diameter. The crystallographic information available in the electron channeling pattern is analogous to that which can be obtained by x-ray diffraction of solid specimens. The advantage of electron channeling is the combination of imaging and orientation information which is available in the SEM. Electron channeling contrast has been the subject of several reviews (Booker, 1969; Newbury, 1974; Joy et al., 1982).