Mechanism of point-defect-driven evolution in ferroelectricity of AlScN films

The performance and reliability of wurtzite-type ferroelectric AlScN films are critically influenced by point defects, particularly nitrogen vacancies (VN·,(··),(···)), although a systematic understanding of their impact remains limited. This study demonstrates the effective modulation of point defects in AlScN films by controlling the Ar/N2 ratio during sputtering and employing successive depositions under a pure N2 atmosphere. We reveal that a high density of point defects induces domain pinning and leads to the split switching current peak. Furthermore, the reduction of point defects facilitates a transition in the switching kinetics from the nucleation-limited switching model to the Kolmogorov–Avrami–Ishibashi model, indicating a defect-mediated evolution from a multi-domain to a more uniform domain structure. Ultimately, this defect-engineering strategy enables an endurance of over 107 cycles in AlScN-based capacitors. These findings establish defect engineering as a viable pathway to optimize performance and endurance in AlScN-based memory devices.