Observation of a hexagonal BN surface layer on the cubic BN film grown by dual ion beam sputter deposition

Cubic-boron nitride (c-BN) thin films were grown by dual ion beam sputter deposition and the growth mechanism was studied using angle resolved in-situ XPS (x-ray photoelectron spectroscopy) analysis. The π bond shake-up satellite of the B 1s peak, which is observed only in a hexagonal boron nitride (h-BN) phase, appeared in the XPS spectrum obtained for the surface layer of the c-BN film. This can be a clear evidence that the c-BN phase grows via the transformation of an initially formed h-BN phase and the transformation is induced by the compressive stress accumulated in the subsurface region during ion bombardment.