Depth resolution in sputter profiling: Evidence against the sequential layer sputtering model

Abstract

The sequential layer sputtering model originally developed by Benninghoven is analysed critically. The validity of the model is checked by comparison with the results of a variety of recently reported depth profiling studies on sandwich layer structures. It is shown that with adequately performed measurements the parameter a representing the “monolayer thickness” is of subatomic dimension and up to an order of magnitude smaller than the relevant lattice constant. Accordingly a is merely a fitting parameter without any physical significance. This result clearly rules out the validity of the model. The cause of non-statistical emission is discussed briefly.