Delta-electron spectra, inelastic cross sections, and stopping powers of ions in silicon: Comparison between different models

The energy spectrum of the δ-electrons ejected by an ion moving in the bulk of a solid is the origin of numerous effects which follow the transport of these electrons. This spectrum cannot be measured directly. Therefore, it should be derived theoretically. The present work aims to investigate the uncertainties introduced when applying commonly used theoretical approaches like BEA, CDFT, and PWBA to calculate δ-electron spectrum. Our calculations show that, above a certain δ-electron energy, the energy spectra of the δ-electrons obtained using the various approaches behave similarly. Below this energy, the spectra found using these approaches differ significantly due to the manner in which the solid state character of the target material is taken into account in each approach. This results in differences in the inelastic cross sections and stopping powers for the ions, which in turn result in different ion track structures. Also discussed in this paper is the effect of the uncertainty in the effective ion charge on the accuracy of ion track calculations. The results obtained for silicon allow estimating the possible uncertainties of the calculated ion track properties and related effects