Molecular dynamics study of the role of ion bombardment in cubic boron nitride thin film deposition

Molecular dynamics simulations of the bombardment of graphitic boron nitride (gBN) with energetic particles of boron and nitrogen have been performed to examine the bombardment-induced transition from gBN to cubic boron nitride (cBN), which is an essential process in deposition of cBN. We have found that the interactions of projectiles with gBN create tetrahedrally coordinated local structures (sp3-formation). The increase in the sp3-content of the target depends strikingly on the projectile energy, while its dependence on temperature appears to be small. We have also found that clusters of sp3-formations are created as a result of continued bombardment, which implies the potential of sp3-formation to achieve cBN nucleation. On the basis of these results, we propose an atomic-scale model of cBN nucleation in which gBN is directly transformed into cBN by successive sp3-formation.