N Penetration Enhances Vacancy Filling, Al/Sc-N Bonding, and Ferroelectric Properties in AlScN Films

We demonstrate, for the first time, that nitrogen(N) penetration into AlScN films significantly enhances ferroelectric performance by suppressing N vacancies and increasing grain size. This is achieved by introducing N from a TiN bottom electrode. As a result, we achieve a remnant polarization (Pr) of 150 μC/cm2, a notable reduction in leakage current, and a high breakdown-to-coercive field ratio (EBD/EC) of 1.85. Material analysis shows that N from the TiN electrode fills N vacancies, suppresses oxidation, and improves the crystalline quality of AlScN, the AlScN/TiN interface, and overall ferroelectric performance. This simple yet effective N treatment strategy advances AlScN material properties and enables next-generation ferroelectric electronics.