The dependence of low-temperature ion mixing of Y/Si bilayers on nuclear energy deposition

Bilayers of yttrium and amorphous silicon were irradiated with 600-keV Ar⁺⁺, Kr⁺⁺, and Xe⁺⁺ ions at temperatures between 80 and 372 K. The mixing rates were considerably larger than rates predicted by a model based on overlapping thermal spikes, as well as predictions generated by an extension of the model to the case of nonoverlapping thermal spikes. However, the experimental mixing rates did exhibit a linear dependence on the nuclear energy deposited at the interface. This agrees qualitatively with the premise of nonoverlapping thermal spikes. We compare our results with other ion-mixed medium-Z, metal/metal systems which also show this tendency.