Fundamental role of ion bombardment for the synthesis of cubic boron nitride films

Boron nitride film growth from B and N ion deposition is studied. We observe growth of the cubic phase (c-BN) between 75 eV and 5 keV and a transition to sp(2)-bonded BN growth between 5 and 10 keV, as predicted by the cylindrical spike model. Atomic rearrangements in thermal spikes are identified as the mechanism responsible for c-BN formation and suppression of defect accumulation. The onset of defect accumulation eventually enhances the growth of sp(2)-bonded BN. The results highlight the fundamental role of the balance between thermal spikes and defect accumulation in ion deposition processes.