Engineering Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> Ferroelectric/Anti- Ferroelectric Phases With Oxygen Vacancy and Interface Energy Achieving High Remanent Polarization and Dielectric Constants
Zefu Zhao, Yu-Rui Chen, Jer-Fu Wang, Yun-Wen Chen, Jia-Ren Zou, Yuxuan Lin, Yifan Xing, C. W. Liu, Chenming Hu
Abstract
In this study, a decreased oxygen vacancy concentration [V<sub>o</sub>] and an increased ZrO<sub>2</sub>-HfO<sub>2</sub> interface area were experimentally and theoretically demonstrated to favor the formation of the ferroelectric orthorhombic phase (FE o-phase), whereas an increased [V<sub>o</sub>] and a decreased ZrO<sub>2</sub>-HfO<sub>2</sub> interface area (by forming alloy) favored the anti-ferroelectric tetragonal phase (AFE t-phase). High remanent polarization (2P<inline-formula> <tex-math notation="LaTeX">$_{r} = 51\,\,\mu \text{C}$ </tex-math></inline-formula>/cm<sup>2</sup>) was achieved, and therefore, a high tunneling electroresistance (TER) ratio (46) was obtained in metal-ferroelectric-metal (MFM) superlattice structures. Moreover, the optimized AFE phase film exhibited a high dielectric constant 50, as measured by non-hysteretic C-V, by using metal-insulator-metal (MIM) capacitors with the ZrO<sub>2</sub>-HfO<sub>2</sub> alloy. The thermal budget used in this study was as low as 450°C.