Density changes in amorphous silicon induced by swift heavy ions

Abstract

Pure and gold-doped amorphous silicon membranes were irradiated with swift heavy ions (75 MeV Ag or 1.1 GeV Au ions) and studied using 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 $\ifmmode\pm\else\textpm\fi{}$ 0.1 nm (core) and 7.0 $\ifmmode\pm\else\textpm\fi{}$ 0.3 nm (total) radius irrespective of gold doping, consistent with radii previously observed [9]. The density in the core is nearly 4% different from that of the surrounding material. The entire track (core $+$ shell) is slightly less dense than the surrounding material, yielding an expansion or hammering constant $A$ of $0.036\ifmmode\pm\else\textpm\fi{}0.003$ ${\mathrm{nm}}^{2}$ per ion track, consistent with the macroscopic ``hammering'' deformation. No tracks were found in samples irradiated with 75 MeV Ag ions, and no signature specific to the gold impurity doping could be observed.