Evolution of polarization switching kinetics in an Al0.8Sc0.2N ferroelectric film with electric field cycling

Wurtzite-structured ferroelectrics have emerged as prominent materials for next-generation microelectronics due to the advantages of large remnant polarization (Pr) and tunable coercive electric field (Ec). However, their polarization switching kinetics and reliability under repeated electrical cycling remain insufficiently understood, posing a challenge for device applications. This work aims to systematically investigate the evolution of polarization switching mechanisms in AlScN thin films during bipolar electrical cycling, and to reveal the potential microstructural origins of the observed fatigue behavior. The switching dynamics were characterized using transient current integration measurements at various electric fields after different cycle numbers. The resulting data show a complete transition process from the Kolmogorov–Avrami–Ishibashi model to the nucleation-limited switching model. The frequency dependence of Ec through triangular wave hysteresis tests also shows the same transition. The convergence of electrical evidence strongly suggests that field-induced aggregation of point defects creates local low-energy nucleation sites. Afterward, these defects severely impede domain wall propagation, thereby driving the observed kinetic transition. Our findings demonstrate a defect-induced transition in the switching mechanism that fundamentally governs the fatigue process in AlScN ferroelectrics. This insight highlights defect engineering as a critical pathway toward enhancing the endurance of wurtzite ferroelectric-based devices.