From our calculations, it seems that the growth of h-BN as a thin film material must be conducted far from thermal equilibrium, highlighting deposition techniques such as sputtering or possibly plasma CVD. From our previously reported growth results, the choice of substrate for h-BN seems critical and the available thickness achievable seems limited. Our calculations indicate that the h-BN lattice seems to be less liable to expansion than the r-BN lattice from our results on thermal expansion of the lattices, indicating that r-BN is less sensitive to lattice mismatch to the substrate. All these conditions are met in the study by Sutter et al. , presenting epitaxial growth of h-BN on Al2O3(0001) substrates with an in-situ epitaxially grown 100 nm Ru(0001) seed layer, using reactive radio frequency magnetron sputtering of a boron target in a nitrogen containing plasma at a temperature of 850 °C. The h-BN films could be deposited to a thickness of approximately 10 BN layers. This corresponds to five unit cells in the cdirection and 3.3 nm, which is close to the 4 nm reported from growth by CVD by the authors .