Damage induced in 100% internal carrier collection efficiency silicon photodiodes by 10-60 keV ion irradiation

We measure the change in the response of 100% internal carrier collection efficiency silicon photodiodes having 60 Å SiO₂ passivation layers due to the damage induced by bombardment with 10-60 keV ions of H, He, N, Ne, and Ar. We find an initially exponential decrease in responsivity with increasing ion fluence Φ and use this to define a damage constant β. The correlation of β with the nuclear stopping power of the incident ion instead of with the total energy lost to nuclear stopping indicates that damage in a channel lying within the n-type silicon near the Si-SiO₂ interface dominates the radiation-induced change in the photodiode response. We use a fluid model of electron transport in the channel to derive a universal curve to describe the damage as a function of ion fluence and to show that the damage constant β is proportional to the damage cross section. Over the energy range of this study, damage cross sections of N⁺, Ne⁺, and Ar⁺ are 10-100 times that of He⁺, and ~1000 times that of H