Fast heavy ion induced interface mixing in thin-film systems

Thin layer systems (Fe2O3/SiO2, NiO/SiO2, Cu2O/SiO2, ZnO/SiO2, Fe/SiO2, Ni/SiO2, Cu/SiO2, Ni3N/SiO2, Ni3N/Si3N4, Ni3N/SiO2, Ni3N/SiC and Ni3N/Si) have been irradiated with Ar, Kr, Xe and Au ions in the energy range from 90 up to 350 MeV. Interface mixing was observed above a threshold value (Sec) of the electronic stopping power, which is determined by the less sensitive component with respect to electronic energy deposition. The estimation of an effective diffusion constant supports the assumption that efficient mixing occurs by transient interdiffusion in a molten track as soon as the electronic energy loss in both layers exceeds the respective track formation threshold. Above the threshold mixing scales with the square of the electronic stopping power (Se). This result again indicates that, according to the global thermal spike model, the one-dimensional energy deposition along the ion path results in a molten track across the interface