Neutron Energy Dependence of Excess Charge Carrier Lifetime Degradation in Silicon

Silicon p-i-n diode-neutron dosimeters were irradiated with monoenergetic neutrons having energies from 0.36 to 4.77 MeV. The variation with neutron energy of the damage coefficient for diode storage time, αT = Δ(l/Ts)/φ, and diode forward voltage sensitivity at constant current, S = #x00394;Vf/φ, were determined and found to be equal. Since αT; and S are linearly related to the damage coefficient for high level lifetime, αT; = Δ(1/τ)/φ, the variation with neutron energy of αT was also determined. Theoretically, it has been hypothesized that N-T is proportional to N-r(En), the average number of active recombination centers added per cm3 per neutron of energy En incident per cm2. It was further hypothesized that N-r(En) is proportional to E-(En), the average energy given to lattice atoms per cm3 per neutron of energy En incident per cm2. The theory of Lindhard, Nielson, Scharff, and Thomsen together with published values for differential neutron-silicon scattering, was used to calculate E-En). Comparison of theoretical and experimental results shows that αT, S, and E-(En) do indeed have substantially the same neutron energy dependence.