Scanning Electron Microscopy


By detecting cathodoluminescence (CL) in a scanning electron microscope (SEM), pan and monochromatic micrographs and CL spectral analyses analogous to x-ray mode point analyses can be obtained. Complete microcharacterization requires alternate examination of both micrographs and spectra. New techniques for near infra-red CL and low-temperatures to produce sharp spectra are of increasing importance. CL emission is due to electron transitions between quantum mechanical states so the radiative defects present can be unambiguously identified at liquid helium temperatures. Strongly luminescent impurities can be detected to below one part in 108. This is 104 times as sensitive as the x-ray mode (electron probe microanalysis). Only luminescent impurities can be detected and quantitative analyses by CL have not yet been attempted. There is a rapidly increasing use of the CL mode for the study of industrially important problems and for the study of the electronic effects of dislocations in semiconductors.

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