Modeling the Behavior of Heavy Ions Incident Upon a Novel Detector

Most existing heavy-ion detectors are large, power-driven, and lack scalability. We investigate a novel SONOS (Silicon-Oxide-Nitride-Oxide-Silicon) transistor-based detector design that addresses these limitations by offering passive operation, reusability, and potential for miniaturization. SONOS transistors exhibit threshold voltage shifts when irradiated by heavy ions due to charge loss in the floating gate region, making non-volatile flash memory devices composed of SONOS transistors strong candidates for heavy-ion radiation sensing. These devices have demonstrated resilience to permanent damage under irradiation, enabling reliable reuse through standard charge injection processes. In this study, we simulate the effects of heavy-ion radiation on SONOS transistors to deepen the understanding of these interactions. The device is modeled using DEVSIM, a drift-diffusion-based semiconductor simulation tool. The interaction with heavy ions is simulated by removing cylinders of charge from the charge trapping region. Several different orientations of the removed charge were tested. Device properties, such as threshold voltage shifts, are numerically calculated for each charge orientation and compared to one another. Here, the simulation agrees with experimental results, as it was found that when you remove charge from the charge trapping region, the threshold voltage tends to decrease. Several statistical analyses were performed to evaluate the probability of each charge orientation. Past experimental data was recreated via simulation and statistical analysis, with similar trends. The insights gained from these simulations will inform future experimental testing and the design of future detectors of this form.