Mandal B., Philippe A.M., Valle N., Defay E., Granzow T., Glinsek S.
ACS Omega, vol. 10, n° 13, pp. 13141-13147, 2025
Since the discovery of ferroelectricity in HfO<sub>2</sub> thin films, significant research has focused on Zr-doped HfO<sub>2</sub> and solid-solution (Hf,Zr)O<sub>2</sub> thin films. Functional properties can be further tuned via multilayering; however, this approach has not yet been fully explored in HfO<sub>2</sub>-ZrO<sub>2</sub> films. This work demonstrates ferroelectricity in a 50 nm-thick, solution-processed HfO<sub>2</sub>-ZrO<sub>2</sub> 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 ZrO<sub>2</sub> layer can be stabilized by the HfO<sub>2</sub> layer. The film attains a remanent polarization of 9 μC cm<sup>-2</sup> 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.
