Ferroelectric HfO₂–ZrO₂ Multilayers with Reduced Wake-Up

Since the discovery of ferroelectricity in HfO₂ thin films, significant research has focused on Zr-doped HfO₂ and solid-solution (Hf,Zr)O₂ thin films. Functional properties can be further tuned via multilayering; however, this approach has not yet been fully explored in HfO₂-ZrO₂ films. This work demonstrates ferroelectricity in a 50 nm-thick, solution-processed HfO₂-ZrO₂ multilayer film, marking it as the thickest multilayer film to date exhibiting ferroelectric properties. The multilayer structure was confirmed through transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy, with high-resolution TEM revealing grain continuity across multiple layers. This finding indicates that a polar phase in the originally paraelectric ZrO₂ layer can be stabilized by the HfO₂ layer. The film attains a remanent polarization of 9 μC cm^-2 and exhibits an accelerated wake-up behavior, attributed to its higher breakdown strength, resulting from the incorporation of multiple interfaces. These results offer a faster wake-up mechanism for thick ferroelectric hafnia films.