As Figure ) points to a difference in the evolution of the deposition rate with respect to the deposition time between hydrogen-and argon ambient, we deposited boron-carbon films from TMB at 700 °C and a constant TMB partial pressure with different partial pressures of the carrier gas. As the TMB flow is small, varying the carrier gas partial pressure is equivalent to varying the total pressure, while changing the carrier gas flow allows to keep the TMB partial pressure and residence time for the gases in the susceptor constant. For these experiments, a higher partial pressure of TMB was chosen (24 Pa in H2, 34 Pa in Ar). Figure shows that the deposition rate in argon ambient does not depend on the partial pressure of argon. The deposition rate in hydrogen ambient is found to be higher than in argon ambient at low partial pressures, which is expected from hydrogen assisted decomposition of TMB, but it decreases significantly with higher partial pressure of hydrogen. In order to discard the effect of isochronal experiments, similar depositions were performed for 120 min instead of 60 min, resulting in films that were twice as thick. As the depositions are conducted under kinetically limited deposition conditions (Figure ), the deposition rate should ideally solely depend on the deposition temperature and the partial pressure of TMB. In our depositions conducted with hydrogen, we kept both temperature and TMB partial pressure constant, thus the growth rate should not vary in these experiments.(Figure ). In hydrogen ambient, the growth rate decreases proportionally to the logarithm of the partial pressure of dihydrogen 𝑝 𝐻 2 . Therefore, the dependence on 𝑝 𝐻 2 observed in Figure is indicative of a hydrogen-dependent process that disturbs the film deposition. Possible explanations are: i) etching of the film by hydrogen species, ii) hydrogen assisted decomposition pathways of TMB generating species not active in film deposition, iii) hydrogen assisted decomposition pathways of TMB generating species that are active in the film deposition but render surface inactive or iv) competitive adsorption of passivating species on the film surface obstructing further deposition.