Electron and neutron irradiation of boron and phosphorus-doped silicon at 80°K

Conductivity and Hall effect measurements have been made on boron and phosphorus-doped silicon which had been irradiated at 80°k either in a nuclear reactor or with 2 Mev electrons. For the boron-doped samples a significant carrier removal rate attributed to the 10B(n, α)7Li reaction was observed. The carrier removal rates in electron irradiated B and P-doped samples were much smaller than predicted by a calculation based upon one carrier removed for each displacement produced. On the other hand, the fast and thermal neutron carrier removal rates were consistent with such a hypothesis, and it is suggested that the defects introduced by neutron irradiation are small complexes with associated levels deep in the forbidden gap. It is suggested that electron irradiation produces primarily neutral vacancies with levels so close to the valence band that they have no effect on the carrier removal rates in either B or P-doped silicon.