Nanostructures of the turbostratic BN transition layer in cubic BN thin films deposited by low-pressure inductively coupled plasma-enhanced chemical vapor deposition

Abstract

Nanostructures of the turbo-stratic boron nitride (tBN) transition layer in cubic BN (cBN) thin films deposited on silicon substrates by low-pressure inductively coupled plasma-enhanced chemical vapor deposition have been studied by means of cross-sectional high-resolution transmission electron microscopy. The variation of tBN (0002) basal plane orientation at different growth stages, from random to texture and then random again, was observed. Quantitative analysis of tBN orientation revealed that cBN nucleation occurred when approximately 64% of the tBN c axis oriented parallel to the substrate surface in the angle ±10° and the distribution function drawn in a polar diagram was approximated by the function: cos6 (θ). At the interface between tBN and cBN, both hexagonal and rhombohedral configurations were observed, and both were found to act as structural precursors and/or deposition sites for cubic boron nitride nucleation. In addition, the compressed tBN configuration accompanied by d spacing contraction and distortion was directly observed.