In our case, due to the dependence on 𝑝 𝐻 2 , one can assume that the inhibitor species is either directly provided by adsorption of atomic hydrogen produced in gas phase reaction or adsorption of dihydrogen (Reaction rate such as 𝑝 𝑖 = 𝑘 𝑟 𝑝 𝐻 2 𝑥 with 𝑘 𝑟 the rate of reaction and 𝑥 the order of the reaction) or by reaction of hydrogen with TMB or one of its decomposition products, in which case the inhibition behavior should also show a dependence on 𝑝 𝑇𝑀𝐵 (Reaction rate such as 𝑝 𝑖 = 𝑘 𝑟 𝑝 𝐻 2 𝑥 𝑝 𝑇𝑀𝐵 𝑦 or more complex). Deposition experiments with increasing TMB partial pressure (Figure ) shows one 𝑝 𝑇𝑀𝐵 region where the deposition rate is not affected by 𝑝 𝑇𝑀𝐵 and one region where the deposition rate increases with increasing 𝑝 𝑇𝑀𝐵 . This suggests that high enough TMB partial pressure can overcome the inhibition. From this, one can conclude that H2 alone is or provides the inhibitor species. We found similarities with the passivation of group 15 semiconductor surfaces by hydrogen which was extensively studied by Gates and with the hydrogenation of the Si(100)c(4x2) at CVD conditions which occurs up to 800 °C, as shown by Rosenow . Considering only the adsorption of H2, multiplying by a factor of 1 2.9