TCAD simulation of x-ray irradiated n+n Si pixel detector design: Impact on breakdown voltage

Radiation tolerant hybrid pixel detectors require at synchrotron for x-ray imaging. The major challenge is to design a surface radiation hard x-ray pixel detector and operate the detector at a very high voltage in the experiment. Within the photon science collaboration at DESY, Hamburg, it was identified that n+n Si pixel detector design is a first option to get high charge collection efficiency. In this paper, we have investigated the effect of x-ray induced damage in the n+n Fz Si pixel detector irradiated by 5 MGy X-ray dose using TCAD device simulation. The layout of design is equipped with multiple guard ring, symmetric metal overhang, current terminating ring, and current ring in such a way, to get 0 V at the cut edge of the detector. We implemented the experimentally verified radiation damage microscopic model in TCAD for the understanding of the electrical behavior of n+n Si pixel detector design. The results are shown on the electrostatic potential, space charge distribution, electron density and electric field distribution at the cut-edge inside the pixel detector at 1000 V, and it shows that the detector can work up to 1000 V without any avalanche breakdown.