compared to N2 (0.0268 Wm -1 deg -1 ) and Ar (0.0185 Wm -1 deg -1 ) could explain the better crystallinity observed when H2 was used compared to N2 and Ar. The higher crystallinity observed when N2 was used, compared to when Ar was used, is then ascribed to the higher thermal conductivity of N2 compared to Ar. Kinetics simulations were used to obtain an atomistic level understanding of the surface chemistry (Fig. ). Starting from a fully saturated surface (i.e. in the model 4 CH3 groups at 4