Modeling of the frequency dependent C-V characteristics of neutron irradiated p+-n silicon detectors after the type inversion in the space charge region

The modeling of the frequency dependent C-V characteristics of neutron irradiated p⁺-n silicon detectors is extended to the case of high neutron fluences (Φ_n>8×10¹² n/cm²) where the effective doping concentration N_eff in the space charge region (SCR) exhibits a net acceptor state (or “p” type), while the resistivity in the electrical neutral bulk (ENB) approaches intrinsic due to the perfect compensation of all deep levels in the condition of no band bending (or no field) and therefore no Fermi level crossing for any deep levels. The C-V characteristics are still frequency dependent, but the deep level that is responsible for it may be different from the one before the type inversion in the SCR. N_eff in the SCR may be dominated by an acceptor level, such as V-V^-, whose concentration is proportional to the neutron fluence. The contribution of the high resistivity ENB to the frequency dependence have also been discussed