THE INFLUENCE OF DIFFRACTION EFFECTS ON QUANTITATIVE AUGER-ELECTRON SPECTROSCOPY

In Auger electron spectroscopy, both the primary electrons entering the sample and the Auger electrons leaving the sample may suffer strong diffraction effects. On well‐ordered single‐crystal surfaces, diffraction effects may result in variations in the intensity of an Auger peak by a factor of up to two or more when the incident beam direction is varied by a few degrees. The large angular acceptance angle of most Auger spectrometers normally averages out any diffraction effects of the Auger electrons themselves. Diffraction effects of the primary electron beam (commonly called channelling) may be described qualitatively in terms of the two‐beam theory of electron diffraction. A more exact representation requires a multiple beam calculation similar to that used in electron microscopy. For quantitative AES it is essential to establish whether diffraction is likely to influence the results and, is so, to take appropriate steps to eliminate or at least to minimize its effect. On the other hand, these channelling effects provide valuable information about the near‐surface order of the sample and potentially provide a technique complementary to x‐ray photoelectron diffraction. Copyright © 1990 John Wiley & Sons Ltd.