Ion-beam-enhanced adhesion of iron films to sapphire substrates

The effect of implantation of different ion species on the adhesion of iron films to sapphire substrates was investigated. The implantation energies were adjusted to ensure that the ion concentration profiles, damage profiles, and recoil distributions were the same for each species. For all implantations, the peak ion concentration was at the film-substrate interface. The adhesion of the films was measured by a pull test and a scratch test. For a fluence of 1x1015 ions cm-2, implantation of chromium (300 keV) and iron (320 keV) increased the bond strength whereas implantation of nickel (340 keV) did not. The effect is proposed to be due to changes in the interfacial energy resulting from the presence of the ion species at the interface. Only a narrow zone is affected; the mixing at the interface is less than 10 nm. (orig.)