Radiation Defect Introduction Rates inn- andp-Type Silicon in the Vicinity of the Radiation Damage Threshold

Abstract

Radiation defect introduction rates have been studied in $n$- and $p$-type silicon by analyzing the effects of electron irradiation on diffused $n$ on $p$ base and $p$ on $n$ base silicon junctions. The electron energy was varied between 125 and 800 keV; this range included the silicon radiation damage threshold. Plots of the product of the probability of producing a defect and the minority capture cross sections of the defects in the two kinds of junctions exhibited similar dependence on electron energy. However, the magnitudes of these products differed by a factor of about 200 in the two structures, the $n$ on $p$ base junctions exhibiting the slower decay rate. It is shown that although the microscopic nature of the radiation defects may differ in $n$- and $p$-type silicon, the rate-determining process is the same in both kinds of material. This process must be the production of vacancy-interstitial pairs as a result of Coulomb scattering by the high-energy electrons. However, the shape of the curve relating the probability of defect introduction to electron energy does not agree with theoretical curves, this in spite of a large increase in reliability of data over previously reported experiments in silicon.