ScholarWorks@숙명여자대학교

초록

Understanding and controlling oxygen exchange at the interface of Hf x Zr1-x O2 (HZO) are critical for stabilizing ferroelectricity in ultrathin films. In this work, we demonstrate that functional capping layers serve as active oxygen reservoirs that modulate the tetragonal to orthorhombic phase transition in both solid solution (SS) and nanolaminate (NL) HZO films. X-ray photoelectron spectroscopy reveals distinct reducibility trends among the capping materials, directly correlating oxygen transfer with changes in crystallinity, grain morphology, and ferroelectric behavior. Comprehensive structural and electrical analyses using X-ray diffraction, atomic force microscopy, transmission electron microscopy, energy-dispersive spectroscopy, and polarization-electric field curve measurements show that WO3 delivers stronger oxygen injection capability and yields superior ferroelectric response in SS-HZO, whereas Nb2O5 optimizes remnant polarization in NL-HZO. Moreover, engineering the sublayer thickness in NL-HZO enables a tunable balance between improved ferroelectric behavior and enhanced reliability. These findings establish oxygen-transfer engineering via functional capping layers as a powerful design principle for achieving robust and energy-efficient ferroelectricity in sub-6 nm HZO, offering a promising pathway toward next-generation ultralow-power ferroelectric memory technologies.

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