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In situ Reflection Electron Energy Loss Spectroscopy (REELS) analyses, performed at various primary electron energies, enable us to distinguish between sp 3 and sp 2 bonding in BN films. Consequences on the c-BN growth modelling are discussed based on the result that polycrystalline cubic BN films grown using IBAD always exhibit a superficial zone of three to four sp 2 bonded monolayers. Increasing the ion energy enlarges the sp 2 superficial zone, while ion beam etching at grazing incidence decreases its thickness. In addition, REELS depth profiling, based on the complementary use of ion beam etching at grazing incidence and REELS analyses, clearly evidences the phase distribution within the c-BN film and reveals a layered structure including a thin layer of a-BN close to the substrate followed by an h-BN basal layer and then by a nearly pure c-BN volume. |
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