Characterization of neutron irradiated, low-resistivity silicon detectors

Abstract

A complete electrical characterization of silicon detectors fabricated using low-( 1.5 kΩ cm) and high-(> 5 kΩ cm) resistivity substrates has been carried out. Measurements have been performed before and after neutron irradiation at several different fluences, up to 3 × 10 14 n cm −2 (1 MeV eq.).Experimental results have been compared with CAD based simulations. A good agreement has been found, thus validating the CAD model predictions.The adoption of low resistivity devices appears to have some definite advantages in terms of depletion voltage, which in turn results in better interstrip capacitance and interstrip resistance.

Recent results for the CMS tracker silicon detectors

“…It is worth noticing that in both cases the inter-strip resistance decreases from a few tens of Gª before irradiation to a few tens of Mª, a value still acceptable to guarantee the isolation from neighbouring strips. No drawbacks concerning leakage current and breakdown performance have been found using low resistivity substrates [9].…”

Study of radiation damage and substrate resistivity effects from beam test of silicon microstrip detectors using LHC readout electronics

“…This irradiation will affect the most important detector parameters, which conversely will give a degradation of detector performances, namely the noise level and the charge collection. Previous studies on electrical performance of microstrip detectors [2] have indicated the advantages of using substrates with low resistivity (1-4 KΩ·cm), related to the possibility of mantaining a relatively low bias voltage after the type-inversion due to radiation damage.…”