Electron Channelling Patterns from Small (10 µm) Selected Areas in the Scanning Electron Microscope

Abstract

THE generation of electron channelling patterns in the scanning electron microscope (SEM) (refs. 1, 2) presents a unique method for obtaining crystallographic information from bulk crystals while viewing directly in the SEM. A technique for generating patterns from small selected areas has been described3 and developed4 to give electron channelling patterns from regions 50 to 100 µm in diameter. In this double deflexion rocking beam method the double deflexion scan system in the ‘Stereoscan’ SEM was modified by attenuating the current in the lower scanning coils so that the scanning crossover point, which normally occurs approximately in the plane of the final aperture (Fig. 1a), was lowered into the specimen chamber (Fig. 1b). A specimen could then be brought into coincidence with the lowered crossover point, and the variations in direction of incidence necessary to generate patterns occurred about a fixed point on the specimen surface.