The growing demand for aerospace data storage necessitates understanding the radiation response mechanisms of 3D NAND technology to design reliable systems. In this study, we observe that irradiation leads to a program-state-dependent threshold-voltage shift: positive for the lowest states (e.g., P1) and increasingly negative for higher states (P2–P7). Furthermore, the recovery effect observed after a 20-h retention period also exhibits program-state dependence, with a greater recovery magnitude in higher states. These phenomena are explained by the interplay of electron dynamics within the charge-trapping layer, the accumulation and detrapping of positive charges within both tunnel and blocking oxides, and the generation and passivation of irradiation-induced nascent defects. The observed net shifts result from the dynamic balance of these competing processes, which is modulated by the state-dependent internal electric field. During irradiation, electron detrapping becomes the dominant mechanism in higher programmed states, leading to a negative threshold voltage shift. In the subsequent recovery phase, the kinetics of hole detrapping from the oxide layers prevail, resulting in a state-dependent positive recovery. These results elucidate post-irradiation charge dynamics and inform mitigation strategies for memory devices in high-radiation applications.
Dong et al. (Sat,) studied this question.