Achieving High Ferroelectric Polarization in Ultrathin BaTiO3 Films on Si

Ferroelectrics show promise for low-power, non-volatile memory technologies. However, material challenges in state-of-the-art ferroelectric hafnates and the high coercive fields required limit their application in devices. Scaling of other candidate materials is challenging, often requiring epitaxial single-crystalline growth using specialised substrates. Here, ferroelectricity is demonstrated in polycrystalline BaTiO₃ films at 10 nm thickness on Si substrates. They exhibit the highest reported remnant polarization for polycrystalline layers, 13 µC cm⁻², a value that is competitive with the epitaxial BaTiO₃ state-of-the-art. This is realised by introducing a novel conductive oxygen barrier, platinum silicide, which also offers strain enhancement of the ferroelectricity. Moreover, it is demonstrated that these layers can be positioned in device-like stacks whilst maintaining ferroelectricity at 10 nm. The findings of polycrystalline perovskite ferroelectric growth in stack configurations akin to those in production flows paves the way for high performance perovskites with greater material complexity.