Wurtzite AlScN/AlN Superlattice Ferroelectrics Enable Endurance Beyond 1010 Cycles

TL;DR

This paper introduces a superlattice design in wurtzite ferroelectrics that significantly enhances endurance, enabling reliable switching beyond 10^10 cycles by stabilizing nitrogen vacancies and preventing defect migration.

Contribution

It presents a novel vacancy-confining superlattice strategy combined with a dynamic recovery protocol to dramatically improve ferroelectric endurance.

Findings

Endurance exceeds 10^10 cycles with minimal polarization loss.

Nitrogen vacancy topology is stabilized by heterostructure energy barriers.

Defect migration and clustering are effectively inhibited.

Abstract

Wurtzite ferroelectrics are rapidly emerging as a promising material class for next-generation non-volatile memory technologies, owing to their large remanent polarization, intrinsically ordered three-dimensional crystal structure, and full compatibility with CMOS processes and back-end-of-line (BEOL) integration. However, their practical implementation remains critically constrained by a severe endurance bottleneck: under conditions where the remanent polarization (2Pr) reaches or exceeds 200 uC/cm^2, devices typically undergo catastrophic failure before reaching 10^8 cycles. Here, we report a vacancy-confining superlattice strategy that addresses this limitation, achieving reliable ferroelectric switching beyond 10^10 cycles while preserving saturated polarization (2Pr >= 200 uC/cm^2). This is achieved by embedding periodic ultrathin AlN layers within AlScN films, forming wurtzite AlScN/AlN superlattices, in conjunction with a dynamic recovery protocol that actively stabilizes the defect landscape throughout repeated cycling. Atomic-resolution imaging and EELS spectrum imaging technique, supported by first-principles calculations, reveal a self-regulated defect topology in which nitrogen vacancies are spatially confined by heterostructure energy barriers and dynamically re-trapped into energetically favorable lattice sites. This dual spatial-energetic confinement mechanism effectively inhibits both long-range percolative migration and local defect clustering, enabling such an ultrahigh endurance exceeding 10^10 cycles and limiting polarization degradation to below 3% after 10^9 cycles. These findings establish nitrogen vacancy topology stabilization as a foundational design principle for reliable operation of wurtzite ferroelectrics, providing a scalable and CMOS-compatible platform for future high-endurance ferroelectric memory technologies.