Enhanced Radiation Hardness in Ferroelectric Field-Effect Transistors Using Compositionally Graded HfZrO x Films

The impact of γ-ray irradiation on ferroelectric field-effect transistors (FeFETs) with different HfZrOx(HZO) compositions was systematically investigated in terms of polarization behavior, endurance, transfer characteristics, and retention. γ-ray exposure induces ionization and defect formation, particularly oxygen vacancies (Vo), whose aggregation into defect clusters significantly degrades device performance. The initial Vo concentration is shown to be a key factor determining radiation hardness. FeFETs with uniform HZO exhibit dense domain formation and severe defect clustering, leading to pronounced remanent polarization (Pr) and memory window (MW) degradation. By contrast, devices with compositionally graded HZO mitigates defect accumulation and those with bottom Zr rich composition demonstrate the best radiation resilience due to their inherently lower Vo concentration. After 1 Mrad irradiation and 107cycling, they retain a large MW of 1.86 V with only 11.1 % degradation of the initial MW. Moreover, retention measurements reveal excellent long-term stability, with ~88.6 % of the MW preserved after 10 years by extrapolation. These results highlight the critical role of Vo control through compositional engineering in achieving FeFETs with superior radiation tolerance.