To test the hypothesis of etching by hydrogen species, we deposited a film for 30 min, removed TMB, exposed the surface to H2 for 60 min and then deposited another 30 min. It resulted in a film of similar thickness as a film deposited for 60 min in the same conditions, within measurement errors, as shown in Figure . As a lower film thickness would be expected if hydrogen species did etch the film, this result suggests that the differences in film deposition characteristics seen between hydrogen-and argon ambient is not explained by etching.