Nucleation of c-BN from PECVD and TACVD growth species:: A theoretical study

The nucleation of cubic boron nitride (c-BN) on the zigzag edges (100) and ((1) over bar 00) of the hexagonal BN (h-BN) prism plane has been theoretically investigated, using a cluster approach and the density functional theory (DFT). Different cubic outgrowths from the edge atoms have been modeled, and the total energies have been set in relation to the total energies for corresponding hexagonal counterparts. The outgrowths were assumed to be derived from the gaseous complexes X2BNH2 and XB(NH2)(2) (X = Cl or H), experimentally observed in TACVD and PECVD reactors. It was found that the nucleation of cubic BN is energetically favorable compared to a continuous growth of hexagonal BN on the two edges investigated. The order of relative energy obtained for the various edges considered is; ((1) over bar 00) > (100). Moreover, the Cl atoms showed the highest ability to stabilize the cubic nuclei, with one exception. However, the energetic differences between the two terminating species were rather small. (C) 2001 Elsevier Science B.V. Ah rights reserved.