Nanoisland nucleation in thermal spike regions on the material surface irradiated by swift heavy ions

Abstract

The energy that is lost by swift heavy ions (SHIs) in a material highly excites its electronic subsystem, while the ion subsystem initially remains almost unperturbed. Subsequent energy transfer from the excited electrons to target atoms may cause a short-term local temperature rise (thermal spike), which, in turn, may induce phase transitions in the nanodimensional region near the ion trajectory. The possibility of nanoisland nucleation within such spikes on the material surface exposed to SHIs is studied. Presumably, the nanoislands appear when the characteristic nucleation time is shorter than the time of spike region cooling. It is shown that the maximal nucleation rate may be observed at a distance of the center of the spike. This may result in the annular distribution of the islands around the SHI trajectory.