The last mechanism to be discussed is ALD growth on top of the inhibitor layer. This necessitates nucleation via physisorbed or chemisorbed precursors interacting with the tail group of the inhibitor followed by regular ALD growth at this site (Fig. .d). This mechanism was studied quite often in computational AS-ALD literature and has first been investigated for SAM inhibitors. Xu and Musgrave first investigated this question and showed that non-alkyl SAM tail groups are prone to be nucleation sites for overgrowth while alkyl groups show very high barriers towards C-H bond cleavage. Also Prinz et al. investigated this question and found very high barriers for the nucleation on alkyl-terminated SAMs. Physisorption on the SAM layer was found as well, which can lead to initiation of ALD growth. The interaction of precursors with SMI-based inhibitors has been studied by many groups (RQ 3a in Tab. 1). Generally, it is assumed that physisorbed precursors are likely be purged away from the inhibitor layer before initiating growth. If covalent bonding of the precursor is thermodynamically feasible and has a reasonable reaction barrier, this is deemed a very likely selectivity-lifting reaction. In several cases, the coreactant H2O is the more reactive species, especially for hydrolyzing ligands at the SMI. As discussed above, this hydrolysis can also be beneficial and increase SMI density.