Engineering switching dynamics and polarization in Hf1-xZrxO2 ferroelectric thin films via vertical compositional asymmetry

초록

HfO2-based ferroelectrics are promising for next-generation nonvolatile memory applications owing to their scalability and compatibility with complementary metal-oxide semiconductor (CMOS) technology. In particular, HfO2–ZrO2 (HZO) nanolaminate structures provide additional flexibility for tuning ferroelectric properties beyond conventional solid-solution films. In this work, we systematically investigate how vertical compositional asymmetry governs the ferroelectric behavior and switching dynamics of HZO thin films using nanolaminate structures with engineered composition gradients. Despite identical thickness and overall compositions, the bottom-layer composition plays a dominant role in determining phase stability, microstructure, and defect distribution. Zr-rich bottom-layer suppresses the monoclinic phase and stabilizes the orthorhombic phase, resulting in an enhanced remanent polarization of up to 53.7 μC/cm2. Nucleation-limited switching (NLS) analysis reveals a significantly narrowed switching-time distribution and more spatially uniform switching behavior, accompanied by improved endurance. These results establish vertical compositional asymmetry as a key design parameter for controlling switching dynamics, polarization, and reliability in HfO2-based ferroelectric devices. © 2026 Elsevier B.V.

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