Fatigue-free ferroelectricity in Hf_0.5Zr_0.5O₂ ultrathin films via interfacial design

Due to traits of CMOS compatibility and scalability, HfO₂-based ferroelectric ultrathin films are promising candidates for next-generation low-power memory devices. However, their commercialization has been hindered by reliability issues, with fatigue failure being a major impediment. Here, we report superior ferroelectric performances with fatigue-free behavior in interface-designed Hf_0.5Zr_0.5O₂-based ultrathin heterostructures. A coherent CeO_2-x/Hf_0.5Zr_0.5O₂ heterointerface is constructed, wherein the oxygen-active, multivalent CeO_2-x acts as an "oxygen sponge", capable of reversibly accepting and releasing oxygen ions. This design effectively alleviates defect aggregation at the electrode-ferroelectric interface and reduces coercive field, enabling improved switching characteristics and exceptional reliability. Further, a symmetric capacitor architecture is designed to minimize the imprint, thereby suppressing the oriented oxygen defect drift. The two-pronged technique prevents intense fluctuations of oxygen concentration within the device during electrical cycling, suppressing the formation of paraelectric phase and polarization degradation. The interfacial design technique ensures superior switching and cycling performances of Hf_0.5Zr_0.5O₂ capacitors, embodying a fatigue-free feature exceeding 10¹¹ switching cycles and an endurance lifetime surpassing 10¹² cycles, along with excellent temperature stability and long retention. These findings pave the way for the development of high-performance and ultra-stable hafnia-based ferroelectric devices.