Boosting the memory window of ferroelectric tunnel junctions via ultra-thin SiO₂ interfacial layer engineering

Achieving a high ON-state current and a large ON-OFF current ratio simultaneously is a critical challenge for ferroelectric tunnel junctions (FTJs). The performance is fundamentally limited by the trade-off between maximizing tunneling current and maintaining stable polarization, which is dictated by the interfacial layer (IL) material properties and band diagram engineering. In this work, we propose and validate a strategic IL design utilizing an ultrathin, low-permittivity silicon dioxide (SiO₂) film deposited by Atomic Layer Deposition (ALD) in an HZO-based FTJ. Theoretical calculations confirm that a lower permittivity and higher electron affinity of the SiO₂ effectively modulate the electric field distribution. The 1 nm SiO₂ device exhibits superior performance, achieving a high ON-OFF ratio of 3400 × and a significantly enhanced ON-state current (9 × higher) compared to the 1 nm Al₂O₃ counterpart at 1.5V. Our findings establish the 1 nm ultrathin ALD-SiO₂ as a highly effective solution for concurrently enhancing the ON-state current and ON-OFF ratio, highlighting a pathway toward high-performance, reliable, and scalable FTJs for advanced non-volatile memory applications.