Since the m/z = 30 is expected to be higher than the m/z = 29 peak in the mass spectrum of C2H6 , i.e., the protonated ligand, we propose that the high intensity observed for m/z = 29 (Fig. ) is explained by ethyl groups eliminated from the surface during the ALD process. We speculate that the dissociative adsorption of TEG, forming surface ethyl groups, could allow for the desorption of intact ethyl radicals (C2H5). According to the mass spectrometry results (Fig. ), the C2H5 signal is already fully developed at temperatures as low as 200°C and stays rather constant up to 400°C, suggesting that TEG could undergo dissociative adsorption at or above 200°C. Surface ethyl ligands can also desorb as ethane (C2H6) after reacting with surface hydrogen (Fig. ). As this reaction depends on the availability of a nearby surface hydrogen, it is reasonable to expect it to be less frequent, and a lower intensity for m/z = 30 (C2H6) compared to m/z = 29 (C2H5) is also noted in Fig. . We noted a higher intensity for the C2H6 signal at 400°C than at lower temperatures (Fig. ), which could be related to precursor decomposition. Stegmuller et al. 2014 studied the decomposition pathways of TEG using DFT, they concluded that the H2 assisted elimination of C2H6 is thermodynamically favored for all three ethyl ligands at 400 °C. We note from our previous study on this ALD process that the upper limit of the temperature window where the surface chemistry is self-limiting, i.e., the so-called ALD window, seems to be 325-350 °C. Thus, we expect very limited stability for any chemisorbed TEG at 400 °C.