Nitrogen profiles in materials implanted via plasma-based ion implantation

The lifetime of metallic components can be drastically increased by surface treatments ensuring a low friction coefficient, surface hardening and an anticorrosion coating. A promising method for such surface modifications is plasma-based ion implantation (PBII) of nitrogen. In order to improve and to obtain a better understanding of such a treatment, we have performed nitrogen implantation in different materials at various ion energy values using pure nitrogen and N2/H2 gas mixture plasmas. Fe and Ti samples were simultaneously treated in a large-volume PBII reactor in which the plasma is excited at the distributed electron cyclotron resonance. Si substrates were also implanted in order to characterize the nitrogen implantation efficiency by Fourier-transform infrared (FTIR) analysis. Profiles of the relative concentration of elements in the samples were deduced from X-ray photoelectron spectroscopy (XPS) analysis as a function of depth. The absolute concentration of implanted nitrogen was also obtained by nuclear reaction with 15N atoms implanted in metals via PBII from a 15N2/14N2 gas mixture. These results can be very useful for calibrating and improving PBII surface treatments of materials.