The EELS elemental depth profile for a triangular pyramidal structure from a BN grown from TMB on c-plane sapphire is shown in Fig. . In contrast to the terminated h-BN, the pyramidal structure incorporates negligible carbon. Note that this elemental profile is acquired from the same sample as the profile shown in Fig. . The EELS depth profiles for the pyramidal structures in the other samples, aligned with their respective HRTEM micrographs, can be found in Figs. : Raman spectra taken from all BN films and a bulk BN reference sample. From top to bottom -Bulk h-BN sample, BN on c-plane sapphire grown using TMB, BN on c-plane sapphire grown using TEB, BN on a-plane sapphire grown using TMB and BN on a-plane sapphire grown using TMB. The sp 2 -BN Raman peak at 1370 cm -1 is observed for all the grown films and appears unshifted from the corresponding peak in the reference bulk h-BN sample. The broad band peaking around 1580 cm -1 observed in all samples is indicative of the G band of amorphous carbon.