Characterization of irradiated p-type silicon detectors for TCAD surface radiation damage model validation

In this work we address the effects of surface radiation damage on detectors fabricated on high-resistivity p-type FZ ⟨100⟩ substrates by Hamamatsu Photonics (HPK) and by Infineon Technologies (IFX). Test structures underwent a wide set of measurements before and after X-ray irradiation with doses from 0.05 to 100 Mrad (SiO2) in order to extract the integrated interface trap density (NIT) and the oxide charge (QOX) peculiar to different vendors, processes and technology options. These parameters can be then used as inputs to TCAD simulation tools. On the basis of the new experimental evidences at these high doses, the TCAD numerical model has been updated considering two main bands of defects, one acceptor and one donor, extended to the whole silicon bandgap and simulating the net effect of the radiation-induced acceptor-like and donor-like defects. The comparison between simulation findings and measured macroscopic electric behaviour, e.g. in terms of C–V curves of MOS capacitors has been used as cross-check for model validation purposes. By means of the same modelling scheme it is possible to reproduce the I–V curves of gated-diodes and the interstrip resistance as a function of the dose from 0.05 to 100 Mrad (SiO2) for the range of technology and design options investigated. The good agreement between simulations and measurements would support the use of this TCAD surface radiation damage model as a predictive tool to optimize the design and the operations of the new generation of silicon detectors for the future High Energy Physics experiments.