The use of chemical vapor deposition (CVD) for the growth of BN thin films on Al 2 O 3 substrates using B 2 H 6 and NH 3 is investigated. The simultaneous supply of B 2 H 6 and NH 3 at a growth temperature of 1360 C under a pressure of 100 mbar results in a rough surface, indicating 3D island growth, regardless of the V/III ratio. Furthermore, a significant decrease in growth rate is observed at high V/III ratios, owing to parasitic reactions between the B 2 H 6 and NH 3 sources. In contrast, alternating the supply of B 2 H 6 and NH 3 results in BN films with honeycomb-like wrinkle patterns. The X-ray diffraction peak intensities from the (002) and (004) planes of hexagonal boron nitride (h-BN) increase as the number of supply cycles is increased. The BN film deposited with 1000 supply cycles shows a Raman shift at 1369 cm À1 with a full width at half maximum of 20 cm À1 , corresponding to the first-order E 2g symmetry vibrational mode in h-BN.

The boron nitride (BN) thin films on Al2O3 substrates grown by chemical vapor deposition (CVD) using alternating supply of B2H6 and NH3 are investigated. A significant reduction in growth rates is observed when the growth temperature (Tg) is decreased from 1360 to 1140 °C, indicating incomplete decomposition of B2H6. The 2θ/ω scans of high‐resolution X‐ray diffraction (HRXRD) reveal that the intensity ratio of 2θ = 26.7°/54.0° is 16, which is close to the theoretical intensity ratio for hexagonal BN (h‐BN) of 17. By reducing Tg, the peak at 2θ = 26.2° is appeared, which is considered to the turbostratic BN (t‐BN). The Raman shift at 1369 cm−1 with a full width at half maximum of 20 cm−1 is analyzed, corresponding to the first‐order E2g symmetry vibrational mode in h‐BN. The high‐resolution transmission electron microscopy (HRTEM) confirms aligned 2D stacking of BN layers and the distance between interlayers of 0.3326 nm. The interlayers of 1.0 nm AlON are identified between BN layers and Al2O3 substrate.

Two different boron precursors, diborane (B2H6) and trimethyl boron ((CH3)3B, TMB), are investigated for chemical vapor‐phase deposition (CVD)‐grown hexagonal boron nitride (h‐BN) on α‐Al2O3 (0001) substrates. The BN layer grown using TMB includes a large amount (2 × 1020 cm−3) of carbon atoms, which is 60 times higher than that in the BN layer grown using B2H6. The X‐ray diffraction 2θ/ω scans for BN film grown using B2H6 exhibit the h‐BN (002) peak. The BN film obtained using TMB includes turbostratic BN (t‐BN). The E2g Raman peak frequencies in B2H6 and TMB h‐BN are observed at 1368.8 and 1369.7 cm−1, respectively. The Raman peak shift to a higher frequency indicates that a larger compressive strain is induced using TMB than using B2H6. The full width at half maximum of the B2H6 and TMB Raman peak frequencies is 21.8 and 42.7 cm−1, respectively. The cathodoluminescence spectra of B2H6 h‐BN show the band‐edge emissions at 225 and 232 nm, whereas only a 300 nm broadband is obtained in TMB h‐BN. It is suggested that the carbon atoms in TMB prevent the formation of highly crystalline h‐BN thin films.