Dependence of the a.c. conductance of neutron irradiated silicon detectors on frequency and temperature

The effect of neutron irradiation of fluence Φ = 1.2 × 1014 n/cm2 on the conductance, G (of admittance Y = G + jB, where B is susceptance), of silicon detectors, as a function of angular frequency (ω) and temperature (T), was studied. By comparing the measured data of G as a function of ω of non-irradiated and irradiated detectors, at the above-mentioned Φ, the influence of irradiation on the dependence of the conductance G(ω) on temperatures 270 K ≤ T ≤ 10 K, was found. The measured data were fitted with the calculated G(ω) of non-irradiated silicon detector, assuming an equivalent diagram of capacitance (Cd) of junction p+-n-n+, in series with the impedance of the bulk (non-depleted) silicon. At temperatures T ≤ 50 K, G(ω) changes as compared with G(ω) at larger temperatures. At very low temperatures, T ≤ 20 K, saturation of G(ω) was found. This is due to the freeze-out effect which appears at this very low temperatures. ements of G(ω) of irradiated samples (Φ = 1.2 × 1014 n/cm2), show deviations from the calculated data already at high temperatures (T ⋍ 270 K) and saturation of the dependence of G as a function of ω for T ≤ 50 K.