Compensation for radiation damage of SOI pixel detector via tunneling

Abstract We are developing a method for removing holes trapped in the oxide layer of a silicon-on-insulator (SOI) monolithic pixel detector after irradiation. Radiation that passes through the detector generates positive charge by trapped holes in the buried oxide layer (BOX) underneath the MOSFET. The positive potential caused by these trapped holes modifies the characteristics of the MOSFET of the signal readout circuit. In order to compensate for the effect of the positive potential, we tried to recombine the trapped holes with electrons via Fowler–Nordheim (FN) tunneling. By applying high voltage to the buried p -well (BPW) under the oxide layer with the MOSFET fixed at 0 V, electrons are injected into the BOX by FN tunneling. X-rays cause a negative shift in the threshold voltage V th of the MOSFET. We can successfully recover V th close to its pre-irradiation level after applying V BPW ≥ 120 V . However, the drain leakage current increased after applying V BPW ; we find that this can be suppressed by applying a negative voltage to the BPW.