Tailoring Ferroelectric Performance and Domain Structure Ordering in HZO Capacitors via 2D-WS₂ Multifunctional Layer

In this study, we propose a high-performance and reliable ferroelectric capacitor based on Hf<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub>Zr<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>1</roman>-<i>x</i></sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> (HZO) integrated with an ultrathin multifunctional 2D-WS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> layer. The WS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> layer, positioned at the interface between the bottom electrode and HZO, serves a multiple function. First, the WS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> acts as a protective layer, effectively suppressing the formation of interfacial defects, such as oxygen vacancies and dead layers during the device fabrication process. Second, this layer functions as a seed layer, promoting the growth of vertically aligned HZO domain structures and enhancing the ferroelectric crystallinity of HZO. This approach addresses key limitations in conventional HZO, including interfacial instability, random domain distribution, and inconsistent switching behavior. Our experimental results reveal significant improvements in ferroelectric performance, achieving stable endurance exceeding 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>12</roman></sup> cycles while maintaining a high remanent polarization (2P<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>r</roman></sub> > 50 μC/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sup>). Additionally, long-term retention performance is expected to exceed ten years at 85 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∘</sup>C. Furthermore, the integration of a WS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> interface layer demonstrates excellent device-to-device uniformity and consistency, even in nanoscale HZO device structures. This work provides new insights into the development of high-performance ferroelectric nonvolatile memory technology by highlighting the multiple advantages of the WS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> layer, which enhances interface stability and facilitates vertical domain alignment.