Ion irradiation during a solid state amorphization reaction

Abstract Thin film bilayers of cobalt and zirconium on sapphire substrates were irradiated during diffusion anneals at different temperatures. The irradiations were performed with 500 keV Xe + and 200 keV Ne + at dose rates of (2–20) × 10 10 ions cm −2 s −1 , corresponding to around 10 −4 displacments per atom per second. The evolution of an amorphous layer was followed by Rutherford backscattering spectrometry, and the absence of intermetallic phases was proved by transmission electron microscopy. Even at maximum doses, the irradiation as such does not cause appreciable ion mixing. However, the thermal diffusion is increased up to an order of magnitude. In contrast, irradiation with 10 14 –10 15 ions cm −2 before heating does not change, or even lowers, the interdiffusion in a solid state amorphization reaction. We suggest that the enhanced thermal diffusion is due to irradiation-induced vacancy-like defects.