Sub-Nanometer Ferroelectric Tunnel Junctions With Record-High on-Current Density Through Synergistic Microwave...

High-density memory systems require a high on-state current density (J_on) to ensure fast read speeds and large sensing margins in cross-point array applications. However, achieving high J_on in atomically thin ferroelectric tunnel junctions (FTJs) remains an unmet challenge, hindered by parasitic interfacial layer (IL), depolarization fields, and phase instability that favors the non-ferroelectric tetragonal phase. Here, a record-high J_on operation in sub-nanometer FTJs is enabled by combining aggressive device area scaling with low-temperature microwave annealing. This approach effectively suppresses IL growth, reducing the IL thickness from 0.94 to 0.41 nm, and simultaneously enables a robust orthorhombic phase transition under high electric fields (>15 MV cm^-1) without dielectric breakdown. By leveraging interface engineering and extreme area scaling, ∼0.9 nm FTJ achieves a record-high J_on exceeding 10⁵ A cm^{- 2} at low voltage (∼0.4 V) while maintaining a stable on/off ratio (>15). This strategy also induces exceptional endurance (>10⁸ cycles) and retention (projected ∼10 years at 85°C), attributed to the reduced depolarization fields. Furthermore, simulations based on experimental data provide guidelines for achieving ideal FTJ performance at the ultimate scaling limits. Our comprehensive study establishes a clear pathway toward reliable FTJ memory suitable for high-density array applications without additional material complexity.