Integrating ferroelectric Hf_0.5Zr_0.5O₂ films with SrTiO₃ by two-dimensional electron gas at interfaces

Integrating multiple functionalities within a single electronic device remains a pivotal research focus, particularly for achieving the coexistence of ferroelectricity and metallic conductivity. As symmetry-broken systems, complex oxide interfaces exhibit diverse correlated phenomena that enable the coupling of distinct properties. Here, we fabricate Hf_0.5Zr_0.5O₂/SrTiO₃ heterostructures with reproducible metallic two-dimensional electron gas (2DEG) at their interfaces. By employing the interfacial 2DEG as the bottom electrode in a parallel-plate capacitor configuration, the fabricated Pt/Hf_0.5Zr_0.5O₂/2DEG/SrTiO₃ devices demonstrate pronounced ferroelectricity in Hf_0.5Zr_0.5O₂ films. Elucidating the mechanism of the coexistence of metallic conductivity and ferroelectricity at the interfaces is crucial for advancing ferroelectric metals in complex oxides and developing multifunctional devices.