Emergence of strong ferroelectricity in pristine HfO2 via interfacial elemental diffusion

Abstract

HfO2-based ferroelectric thin films demonstrate exceptional potential for nonvolatile memory applications, owing to their outstanding stability and superior compatibility with conventional semiconductor fabrication processes. Nevertheless, pure HfO2 displays weak ferroelectricity at room temperature and atmospheric pressure without any external conditioning, thus necessitating structural modifications to enhance ferroelectricity. In this work, we propose a novel approach to induce the ferroelectric orthorhombic phase in HfO2 by introducing a Zr interlayer, offering a new pathway to enhance its ferroelectric performance. Bilayer Zr-interlayered HfO2 thin films were fabricated via magnetron sputtering, where post-deposition annealing promotes Zr diffusion, facilitating the stability of the metastable ferroelectric phase. Electrical characterization demonstrates a remanent polarization of 15 μC cm−2 at 2.3 MV cm−1 and a coercive field of 1.3 MV cm−1, confirming the emergence of strong ferroelectricity. Notably, the Zr interlayer eliminates the need for a dedicated bottom electrode, allowing direct deposition on heavily doped silicon substrates and enhancing compatibility with complementary metal–oxide–semiconductor (CMOS) integration. This work provides an effective method to induce strong ferroelectricity in pristine HfO2 thin films.