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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/cm2) 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.
The AlScN/AlN/AlScN multi-layer decouples the polarization-coercive field relationship. Increasing the AlN ratio enhances the memory window and retention in ferroelectric thin-film transistors, demonstrating their potential for memory applications.
Details
Indium gallium zinc oxide;
Electrodes;
Multilayers;
Decoupling;
Ferroelectricity;
Polarization;
Semiconductor devices;
Thin films;
Gallium;
Transistors;
Ferroelectrics;
Silicon nitride;
Transmission electron microscopy;
Performance enhancement;
Piezoelectricity;
Fourier transforms;
Field effect transistors;
Thin film transistors;
Electric fields;
Coercivity;
Ferroelectric materials;
Retention;
Interfaces
; Ryoo, Seung Kyu 1 ; Yeom, Min Kyu 1 ; Lee, Suk Hyun 1 ; Choi, Wonho 1 ; Kim, Yunjae 2 ; Choi, Jung-Hae 3
; Xin, Tianjiao 4 ; Cheng, Yan 4 ; Hwang, Cheol Seong 1
1 Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul, South Korea (ROR: https://ror.org/04h9pn542) (GRID: grid.31501.36) (ISNI: 0000 0004 0470 5905)
2 Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University, Seoul, South Korea (ROR: https://ror.org/04h9pn542) (GRID: grid.31501.36) (ISNI: 0000 0004 0470 5905); Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, South Korea (ROR: https://ror.org/04qh86j58) (GRID: grid.496416.8) (ISNI: 0000 0004 5934 6655)
3 Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, South Korea (ROR: https://ror.org/04qh86j58) (GRID: grid.496416.8) (ISNI: 0000 0004 5934 6655)
4 Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai, China (ROR: https://ror.org/02n96ep67) (GRID: grid.22069.3f) (ISNI: 0000 0004 0369 6365)