Kim Kyung Do, Ryoo Seung Kyu, Yeom Min Kyu, Lee Suk Hyun, Choi Wonho, Kim Yunjae, Choi Jung-Hae, Xin Tianjiao, Cheng Yan, Hwang Cheol Seong
Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul, South Korea.
Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, South Korea.
Nat Commun. 2025 Aug 11;16(1):7425. doi: 10.1038/s41467-025-62904-6.
AlScN emerges as a promising material for ferroelectric field-effect transistors due to its high coercive field (>6 MV/cm). However, its high remanent polarization (>100 μC/cm) can degrade memory window and retention, limiting its use in memory applications. This study introduces an AlScN/AlN/AlScN multi-layer designed to decouple the polarization and coercive field, thereby increasing the coercive field while maintaining polarization value. The AlN layer switches ferroelectrically in response to the AlScN layer's switching, even though a single AlN layer is piezoelectric. The lower dielectric constant of AlN compared to AlScN increases the coercive field of the stack, while the AlScN layer primarily determines the polarization. This study shows that increasing the AlN ratio in the multi-layer significantly enhances the memory window and retention performance of ferroelectric thin-film transistors with amorphous indium-gallium-zinc-oxide channels. A maximum memory window of 15 V is achieved, enabling the development of a penta-level cell for next-generation storage.
由于其高矫顽场（>6 MV/cm），AlScN成为铁电场效应晶体管的一种有前景的材料。然而，其高剩余极化（>100 μC/cm）会降低记忆窗口和保持性能，限制了其在存储器应用中的使用。本研究引入了一种AlScN/AlN/AlScN多层结构，旨在解耦极化和矫顽场，从而在保持极化值的同时提高矫顽场。尽管单个AlN层是压电的，但AlN层会响应AlScN层的切换而进行铁电切换。与AlScN相比，AlN较低的介电常数增加了堆叠结构的矫顽场，而AlScN层主要决定极化。本研究表明，增加多层结构中AlN的比例可显著提高具有非晶铟镓锌氧化物沟道的铁电薄膜晶体管的记忆窗口和保持性能。实现了15 V的最大记忆窗口，从而能够开发用于下一代存储的五电平单元。
