In recent years, it became apparent that the degree of dimerization has a strong influence on the reactivity of the precursor since it (i) reduces the Lewis acidity and thus the surface reactivity of the precursors and (ii) increases the steric bulk which is important for inhibitor-based approaches. Thus, several studies investigated the influence of dimerization on the selectivity in AS-ALD process. The dimerization tendency is typically expressed as dissociated dimer fraction (DDF) and is derived from the equilibrium constant K of the dimerization reaction: