Dual Ferroelectric\nPolarization and Dielectric Response\nImprovement in Epitaxial Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>/HfO<sub>2</sub> Nanolaminates

Nanolaminates based on ferroelectric polycrystalline\ndoped HfO<sub>2</sub> have gained interest because those compounds\nshow enhanced\nfunctional properties. Here, we achieve coexisting improvement of\nremanent polarization and dielectric permittivity in wake-up-free\nepitaxial Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>/HfO<sub>2</sub> nanolaminates with different numbers of HfO<sub>2</sub> nanolayers\nif compared with Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> single\nfilms of equivalent thickness or other reported polycrystalline nanolaminates.\nComprehensive structural characterization reveals that the origin\nof the enhancement must be the larger amount of the orthorhombic phase\nin the nanolaminates. The retention of nanolaminates is greater than\nthat of Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> single films;\nhowever, fatigue is larger and ferroelectric switching is slower in\nthe nanolaminates compared with single layers. The present work reveals\nnanolamination in high-quality films as a strategy to increase dielectric\npermittivity without important degradation of other functional properties.