Study of radiation effects on bipolar transistors

Abstract

In this paper it was shown that the irradiation with neutrons and carbon ions leads to gain degradation in bipolar transistors due to generation of defects. The density of these generated defects is independent of the type of irradiation (neutrons or carbon ions). Thus, it is possible to evaluate Δ(1/ β), once the expected Frenkel pair density is known. The dependence of the damage constant on collector current is a power law function, with the exception of the lateral pnp transistors, that shows a higher sensitivity to radiation and a different behaviour. Neutrons give a smaller density of Frenkel pairs (CF) than the two sorts of carbon ions of high energy (CHE) and medium energy (CME). It was found that CME causes a higher concentration of CF. The calculated ratio R=CF/ Φ, where CF is the Frenkel pair density and Φ fluence does not depend on Φ, for a given type of radiation. However, it depends on the incoming particle type. Its smallest calculated value was obtained for neutrons ( R=6.1×10), which increases to 1.25×10 3 for CHE and to 1.1×10 4 for CME.