Structural characteristics and polarization switching behaviors in HfO2-ZrO2 2-ZrO 2 ferroelectric nanolaminates

Hf 0.5 Zr 0.5 O 2 solid solution ferroelectric thin film is an extremely promising candidate for ferroelectric memories due to the high compatibility with silicon-based technology, the large process window, and low crystallization temperature. Recent attentions focus on HfO2-ZrO2 2-ZrO 2 nanolaminates with equal thicknesses of the HfO2 2 and ZrO2 2 layers, which offer opportunities to enhance the ferroelectricity and reliability of the Hf 0.5 Zr 0.5 O 2 solid solution thin films. But their structural characteristics and polarization switching behaviors have not been expounded clearly. In this work, we clarify the local epitaxy relationship between the HfO2 2 and ZrO2 2 layers in the HfO2 2 (4 nm)-ZrO2 2 (4 nm) nanolaminate thin film, as well as the improved crystallinity compared to the 8-nm-thick Hf 0.5 Zr 0.5 O 2 solid solution thin film. These structural characteristics result in the significantly enhanced ferroelectricity and polarization fatigue performances of the HfO2-ZrO2 2-ZrO 2 nanolaminate thin film. Moreover, we find that the polarization switching behavior of the HfO2-ZrO2 2-ZrO 2 nanolaminate follows the nucleation-limited switching model, and demonstrates a strong temperature dependence that the higher operation temperature is, the faster switching speed becomes. This work not only provides the key insights into the HfO2-ZrO2 2-ZrO 2 ferroelectric nano- laminates for memory devices applications, but also contributes to the fundamental understandings of the HfO2- 2- based ferroelectric thin films.