Trap charges in the ferroelectric layer pose a serious threat to the normal operation of HfO₂-based ferroelectric field-effect transistors (FeFETs) in radiation environments. In this work, the influence of ferroelectric-layer traps on the single-event transient (SET) characteristics of HfO₂-based FeFETs is systematically investigated using a calibrated TCAD simulation model. The effects of trap type, energy level, concentration, and energy-level distribution on the polarization behavior, electrical characteristics, transient current response, and charge collection process are analyzed.
The results show that the modulation effect of traps strongly depends on the coupling relationship between trap charge polarity and ferroelectric polarization direction. Donor traps produce positively charged centers after ionization, which enhance the local electric field under downward polarization and increase the polarization magnitude, resulting in a negative shift of the transfer characteristics. In contrast, acceptor traps capture electrons and generate negative charges, thereby suppressing the channel potential and shifting the transfer characteristics toward positive gate voltages.
The single-event transient response exhibits a pronounced asymmetry with respect to trap polarity. Under the downward polarization state, donor traps significantly increase the apparent transient current peak when the trap energy level approaches the middle of the bandgap. The transient peak current increases from approximately 9.5 μA to 23 μA, whereas acceptor traps only produce minor variations. Further analysis indicates that the increase in transient peak current mainly originates from the enhancement of the pre-strike steady-state drain current. Increasing trap concentration or broadening trap energy distribution raises the effective trap charge, which in turn exerts static modulation on the channel surface potential.
After removing the steady-state current background, the net collected charge is found to be nearly independent of trap parameters. The extracted net charge agrees well with the electron current component, indicating that the SET response is dominated by the rapid drift of electrons driven by the local electric field. Moreover, the collected charge distribution is mainly determined by the geometric relationship between the ion strike location and the source/drain junctions, while the influence of ferroelectric polarization remains relatively weak.
These results reveal that the influence of ferroelectric-layer traps on SET behavior follows a static modulation mechanism of “trap characteristics–effective trap charge–conduction baseline–transient current peak”. This work provides physical insights into the radiation response of HfO₂-based FeFETs and offers important references for optimizing device design to improve single-event transient immunity via defect engineering and bias adjustment.