From XRD results on specifically the c-cut and a-cut Al2O3, we can conclude that the out of plane crystalline growth direction for r-BN is still identical, being sp 2 -BN (000ℓ) and sp 2 -BN (0002ℓ), between the two substrates. These substrates also show identical AlN 0002 and AlN 0004 peaks, this result was also observed in a past study on AlN growth on these Al2O3 substrates. The potential for a new growth direction was not realized, but a-cut Al2O3 showed comparable crystal properties to the c-cut with better crystalline quality as supported by the ω-scan (Fig. ) for the growth of r-BN films.