Radiation-induced aggregatization of immobile defects

A model for accumulation kinetics of Frenkel defects (vacancy-interstitial) produced under irradiation in solids is presented and developed. Defects are assumed to be immobile (low temperatures or doped crystal) and their accumulation is restricted by annihilation of dissimilar defects. The limiting case of an instant annihilation is studied. The complete description of a spatial defect distribution employing the joint probability functions permits to establish the connection between an initial spatial distribution within Frenkel pairs and a steady-state defect distribution and concentration under saturation. The greater initial correlation within pairs, the less defect concentration. The model confirms the formation of radiation-induced aggregates of similar defects.