Nucleation study of titanium nitride onto steel using N-15(p,alpha gamma)C-12 resonant nuclear reaction

In this research, titanium nitride is deposited by reactive DC magnetron sp uttering with two original constraints due to the expected industrial appli cation as roll to roll decorative coating of steel: the samples should be g rounded and could not be heated during deposition. The growth of titanium n itride on low-carbon steel has been studied using the N-15(p.alpha gamma)C- 12 resonant nuclear reaction analysis for 429 keV protons. Using gas flow o f isotope N-15 enriched nitrogen during deposition, it is possible to detec t nitride layer of about 0.3 ML (MonoLayer) calculated thickness with the h elp of the above very sharp nuclear reaction. Films from 0.3 ML to bulk-lik e thicknesses deposited on low-carbon steel have been analysed. The spectra obtained were deconvoluted to obtain the straggled energy width and the he ight proportional to the depth of nitride layer and to the N-15 coverage, r espectively. It is then possible to observe the nitride growth onto steel s ubstrates: an island nucleation is followed by coalescence and finally by a continuous growth. These three nucleation steps suggest an island growth m ode, the basis of the well-known columnar structure for sputtered titanium nitride on steel. (C) 2000 Elsevier Science B.V. All rights reserved.