Speaker
Description
Pure and gold-doped amorphous silicon membranes were irradiated with swift heavy ions (75
MeV Ag or 1.1 GeV Au ions) and studied by small angle X-ray scattering. The samples that
were irradiated with 1.1 GeV Au ions produced a scattering pattern consistent with core-shell type
ion tracks of 2.0 ± 0.1 nm (core) and 7.0 ± 0.3 nm (total) radius irrespective of gold doping and
consistent with radii previously observed [Bierschenk et al., Phys. Rev. B 88, 174111 (2013)].
However the core must be less dense than the original amorphous silicon, not more dense as argued
in the same report, because its density is nearly 4 % different from that of the surrounding material.
The compressive stress required to maintain the core 4 % more dense would exceed the yield strength
of amorphous Si. The entire track (core + shell) is slightly less dense than the surrounding material,
putting it under a lateral stress consistent with the macroscopic ”hammering” deformation seen when
tracks overlap. No tracks were found in samples irradiated with 75 MeV Ag ions, and no signature
specific to the gold impurity doping could be observed.
