Description of irradiation damage

Irradiation induced defects present a wide range of sizes and topologies. Light ions or scattered energy transfers caused by alpha, beta or gamma radiation produce dilute damage that can be easily annihilated during subsequent thermal treatments. On the contrary heavy ions and energy transfers concentrated in local regions can produce large defects that may degrade material properties and device performance. The proper knowledge of both the amount and morphology of the generated damage is of fundamental importance to predict the behavior of materials and devices exposed to radiation.

We have developed new criteria to describe damage according to their size, morphology or their excess or deficit of atoms, which allows us to classify the large variety of defects present after irradiation. For example, we can determine the typical size of defect clusters found on an implantation tail or the mean vacancy content of amorphous regions created by heavy particle irradiation, among others. Particularly stable or abundant defect clusters can also be identified, that could later be characterized by more fundamental simulation techniques.

Defects with different sizes and topologies obtained by classical molecular dynamics simulations. Red and blue spheres represent displaced atoms and atoms at their lattice positions, respectively.