Morphotropic phase boundary (MPB)-engineered HfO₂ to reduce coercive field (E_c) for energy-efficient FeFETs

Ferroelectric field-effect transistors (FeFETs) based on Hf_1-xZr_xO₂ are investigated with a focus on morphotropic phase boundary (MPB) engineering to simultaneously enhance polarization and reduce coercive field. A super-laminated HZO/ZrO₂/HZO (HZZ) stack was fabricated by ALD, showing a dielectric constant of 46 and a remanent polarization of 41 μC/cm² with coercive field (E_c) reduced to 0.8 MV/cm. Compared to HZO and HfO₂/ZrO₂/HfO₂ (HZH), HZZ enables a wider memory window of 1.6 V under a smaller applied sweep bias for efficient polarization switching at low operation voltage. Endurance measurements demonstrate stable program/erase cycling up to 10¹¹ cycles with an on/off ratio exceeding 10⁵. These results highlight the HZZ-FeFET as a scalable and energy-efficient device platform, offering robust reliability and promising potential for high-density nonvolatile memory and neuromorphic computing.