Atomic-scale structure at the nucleation site of cubic boron nitride deposited from the vapor phase

Cross-sectional transmission electron microscopy, two-dimensional Fourier a nalysis, and electron energy loss spectroscopy were applied to sputter-depo sited cubic boron nitride (cBN) films in order to investigate the structura l evolution during cBN film growth, especially cBN nucleation on the initia l sp(2)-bonded BN layer adjacent to the substrate. The difference in, the b onding state of each layer and the existence of rhombohedral BN (rBN)-like structure in the turbostratic BN (tBN) layer at the cBN nucleation sites we re clearly ascertained. In addition, strong correlations between rBN{003} a nd cBN{111}, and between rBN{101} and cBN{111}, similar to those predicted for pressure-induced direct diffusionless conversion of rBN to cBN, were al so confirmed. [S0163-1829(99)14015-3].