Identification of atomically sharp concentration steps in solids

Abstract

Controlled sputter removal of a solid in conjunction with one of the recent methods for surface analysis has become the most sensitive technique for the determination of concentration depth profiles and concentration transitions at thin film interfaces [1]. As microsectioning by sputtering occurs at an atomic scale, and as the information depth of the mass spectrometric techniques SNMS and SIMS or of Auger electron spectroscopy AES for appropriate Auger peaks is confined to the first or the first two outermost atomic layers, the identification of atomically sharp concentration steps should be possible in principle. Even when minimizing all interfering instrumental influences (for a recent review see [2]), there exist, however, several physical processes of fundamental nature which cause residual broadening effects in high resolution sputter depth profiling. These processes are always connected with the sputtering mechanism. Their origin and their influences are briefly discussed in the following.