Interface mixing of CuOx/SiO2 bilayers by swift heavy ions

Thin films of CuOx (x = 0, 0.5, 1) on SiO2-substrates were irradiated with heavy ions in the electronic stopping regime (some MeV/amu) and in the nuclear stopping regime (some keV/amu). The irradiation of the oxide layers with Ar, Kr and Xe ions of 90-260 MeV lead to strong interface mixing. The mixing efficiency seems to correlate with the bandgap of the toplayer and the estimation of the effective diffusion constant indicates interdiffusion in molten ion tracks. No mixing was observed after high energy irradiation of Cu/SiO2, which can be explained by the fact that the critical electronic stopping power for track formation has not been exceeded even with 230 MeV Xe ions. Irradiation of CuOx/SiO2 (x = 0, 0.5, 1) with 900 keV Xe in all cases leads to only weak intermixing, which can be explained by the ballistic model. (C) 2002 Elsevier Science B.V. All rights reserved.