NIEL Scaling: Comparison With Measured Defect Introduction Rate in Silicon

At low ion energies, the approximation of independent collisions between atoms starts to break down. The displacement damage threshold seems to be far less steep than the one used traditionally within the BCA approach. It has been shown in a previous paper that the Non Ionizing Energy Loss (NIEL) of low energy electrons is greatly modified by the use of a smoother threshold. In order to validate the approach, NIEL values are compared with a large set of bibliographic data. It is shown that the modified "effective" NIEL model simulates quite well the introduction rates energy dependence for both protons and electrons. The model is able to reproduce the difference in absolute defect introduction rate for n and p-type silicon by means of the parameter (f_surv) that account for the fraction of defect surviving recombination. This difference is then connected to the corresponding discrepancy between the diffusion length damage factors observed in n-Si and p-Si materials. It allows in the case of electrons to scale the diffusion length degradation with a single characteristic curve.