Robust Ferroelectricity in Micrometer–Thick Ce:HfO 2 Films

Abstract HfO 2 –based ferroelectric is extensively studied for semiconductor applications due to its compatibility with complementary metal–oxide–semiconductor technology and stable ferroelectric behavior in the thin films. However, achieving robust ferroelectricity in micrometer–thick HfO 2 –based films remains challenging, as the metastable polar orthorhombic phase is difficult to stabilize in thicker films. In this study, by controlling micro– and nanostructures in crystal grains, 3–µm–thick Ce–doped HfO 2 (Ce:HfO 2 ) films fabricated via chemical solution deposition (CSD) exhibit robust ferroelectricity, characterized by high remnant polarization, low leakage current, and minimal wake–up effect. The films display a distinctive {111}–preferred oriented single crystal–like columnar structures with embedded nanopores, which likely results from competitive grain growth mediated by the surface of the underlayer during the thermal treatment from gel to crystal in the CSD process. This work demonstrates a promising strategy to enable robust ferroelectricity in micrometer–thick HfO 2 –based films and facilitates the expansion of thick–film applications such as piezoelectric devices, pyroelectric devices, electrocaloric devices, and power electronics.