Comparing the GPC between the trenches with different purge durations, it can be noticed that the GPC of the trenches deposited with 5 s purge is higher than that with 1 s purge. We speculate that a longer H2 purge step after Si-pulse would remove more Cl terminations on the surface, replacing them with H terminations. The higher bond enthalpy of the Si-Cl bond (400 kJ/mol) than that of the Si-H bond (323 kJ/mol) 32 means a nonfavored replacement from thermodynamics, suggesting that longer purge time should be able to increase the replacement. The GPC at the lower part of the trenches increases with increasing trench width, which can be explained by a larger gas volume being replaced in a wider trench during the purge, leading to higher degree of surface termination replacement in a wider trench. This effect is more noticeable in the trenches deposited with 5 s purge, presumably because more growth inhibitors are removed from the surface with longer purge, as is described above. The growth mechanism proposed for the 3C-SiC coatings deposited by pulsed CVD is summarized in Figure .