It is therefore hard to judge if CVD in other labs render the same surface morphology as we report in Fig. , we have demonstrated this morphology in previous studies. We suggest that a borane like B2H6 might be a better, albeit possibly more problematic, boron precursor for epitaxial growth of h-BN and r-BN in CVD. Secondly, from our results and with support from Sutter et al. , the growth of h-BN films exceeding a few basal planes on graphene seems unfavorable. The surface carbon of graphene, especially if the graphene is thicker than a single layer, will likely steer the growth towards r-BN instead of h-BN. Since r-BN and h-BN have somewhat different properties, e.g., different bandgaps, and are challenging to distinguish from each other , we call for very careful characterization of any BN films and layers on graphene and other carboncontaining surfaces for correct assignment of the reported properties.