Damage Energy Threshold Anisotropy in Nonionizing Energy Loss Calculation

The nonionizing energy loss (NIEL) commonly used to assess the displacement damage dose (DDD) effects in irradiated devices and materials is based on the definition of single atomic displacement threshold energy (
$E_{\mathrm {d}}$
). The use of a single
$E_{\mathrm {d}}$
value is known to reproduce quite poorly the level of damage induced by electrons. A method to include a damage threshold energy distribution in the calculation of the NIEL is reported. The variability of displacement threshold energies linked to crystallographic anisotropy of the solids is indirectly taken into account. It also enables the Lindhard partition function to be more consistent with both molecular dynamics (MDs) modeling and experimental measurements. Below ~1 MeV, our calculations change significantly the electron’s NIEL, that better match experimental damage factors. The NIEL of protons, for its part, is affected at lower energy (<1 keV).