The concept of non-ionizing energy loss (NIEL) has been demonstrated to be a successful approach to describe the displacement damage effects in silicon materials and devices. However, some discrepancies exist in the literature between experimental damage factors and theoretical NIELs. 60 Co gamma rays having a low NIEL is an interesting particle source that can be used to validate the NIEL scaling approach. This paper presents different 60 Co gamma ray NIEL values for silicon targets. They are compared with radiation-induced increase in thermal generation rate of minority carriers per unit fluence. The differences between the different models, including one using molecular dynamics, are discussed. I.

In GaAs material, the radiation-induced degradations are demonstrated to vary according to the Non Ionizing Energy Loss (NIEL). But some discrepancies are still observed between experimental degradation measurements and predicted NIELs. The used displacement threshold energy (T d ) varies, from one author to another, from 10 eV up to 25 eV. A measurement made with 60 Co gamma rays is used to investigate the relevance of the NIEL scaling law for both electrons and gamma rays. A T d value of 21 eV is found to be the most appropriate value, to properly scale the present experimental degradation measurements.

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