Interface mixing in Ni3N/SiX bilayers induced by swift heavy ions

In order to investigate the swift heavy-ion-induced mixing of nitride coatings we have irradiated Ni3N films on SiO2-, Si3N4-, SiC- and Si-substrates with Ar, Kr, Xe and An ions of energies ranging from 90 to 350 MeV, for which electronic energy loss dominates. The Ni-concentration profiles at the interfaces before and after irradiation were determined by means of Rutherford backscattering spectrometry with 900 keV He2+ ions. In all the cases, strong mixing occurred as soon as a material-dependent threshold S-ec in the electronic stopping power S-e was exceeded. The mixing rate exhibits a squared scaling k = Deltasigma(2)/Phi = eta(2) (S-e - S-ec)(2) and estimation of the effective diffusion constant indicates interdiffusion in molten ion tracks. The threshold value S-ec depends on the substrate material and seems to be determined by its melting point and specific heat. (C) 2003 Published by Elsevier Ltd.