The growth temperature for the process based on TMB was 1400 °C and BN films were grown for 60 min with a process pressure of 50 mbar, while the process based on TEB growth was done at 1485 °C and BN films were grown for 120 min with a process pressure of 70 mbar. The NH3/TMB ratio was 966, while the NH3/TEB ratio was 642. As observed from prior studies, the addition of silane (SiH4) had proved useful to promote better crystallinity in the films grown by this process, hence it was introduced during growth using both the B precursors. Silane (SiH4, 99.999 % purity, 2000 ppm diluted in 99.9996 % H2) was supplied with a flow corresponding to 16.5 sccm 2 minutes before BN deposition.