ScholarWorks@성균관대학교

초록

We report the phase stabilization and capacitance enhancement of electric-field-treated Hf0.5Zr0.5O2 (HZO) bilayer capacitors near the morphotropic phase boundary (MPB). Compositional-asymmetric bilayer structures were fabricated by atomic layer deposition, followed by post-deposition annealing and electric-field cycling. The applied cycling induced irreversible phase transitions between the orthorhombic (o-) and tetragonal (t-) phases, effectively stabilizing the MPB region. A pronounced capacitor wake-up effect was observed, indicating self-optimization under repeated cycling. Structural analyses confirmed distinct bilayer formation and progressive phase evolution, while electrical measurements revealed an enhanced dielectric constant and increased remanent polarization. Importantly, the optimized bilayer exhibited a maximum dielectric constant of similar to 52 at a reduced operating voltage of 2 V, along with improved endurance characteristics. These results demonstrate a viable strategy for engineering high-kappa ferroelectric capacitors with low-voltage operation, making them promising candidates for advanced DRAM and nonvolatile memory applications.

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