Electron spin resonance and transmission electron microscopic results confirmed the presence of a microcrystalline, as well as an amorphous phase, in thin films which had been grown by means of plasma-assisted chemical vapor deposition. Line-broadening effects in hydrogenated and deuterated samples indicated that a broad central line was associated with dangling bonds in the amorphous phase, whereas a 4-line spectrum and a 10-line spectrum was associated with paramagnetic B defect centers in the microcrystalline phase. It was found that the dangling-bond concentration was 10 times higher than the concentration of one-B defects. The hyperfine coupling constant for the one-B center in the cubic microcrystalline regions was only 20% of the previously reported value for a similar center in hexagonal BN. The relative concentrations of the dangling bonds, the one-B centers and the three-B centers depended upon the exact plasma conditions which were used to form the thin films.

S.Lin, I.M.Brown, B.J.Feldman: Solid State Communications, 1995, 96[6], 421-4