Overgrowth of inhibitor layers (Fig. .d) The mechanisms of blocking and unwanted growth on the NGS have been analyzed under ALD conditions with experimental approaches. An analytical model has been proposed fitting experimental data to a set of parameters with the goal to gain insights into possible selectivityreducing mechanisms. It will be shown that computational approaches can complement and complete this picture. The onset of "loss of selectivity" has been defined by Parsons for a value of S < 0.9 (eq. 1.7).