Growing imbedded Ni3C-rich layer with sharp interfaces by means of ion beam mixing of C/Ni layers

C/Ni bilayers of various layer thicknesses (20?40?nm) were ion bombarded using Ga+ and Ni+ projectiles of energies 20 and 30?keV. Ion bombardment resulted in the growth of a Ni3C rich layer with the following features: (a) sharp carbon/Ni3C rich layer interface, (b) the amount of Ni3C produced by the irradiation proportional to the square root of the fluence and dependent on the type of projectile, (c) good correlation between the distribution of vacancies produced by the ion bombardment and the distribution of Ni3C. The formation of the metastable Ni3C compound was explained by a vacancy-assisted process. The sharp interface is the consequence of a relaxation process removing the intermixed Ni from the carbon layer. The square root of fluence dependence of the thickness of the Ni3C-rich layer can be explained by a usual diffusion equation considering moving boundaries.