Hafnia thin films are known to demonstrate excellent performance with strong ferroelectricity and high scalability, making them promising candidates for CMOS-compatible materials. However, the reliability of ferroelectric devices must be further improved. This study developed a HfZrO ferroelectric capacitor with a nanolaminate structure that operated at remarkably low voltages, demonstrating excellent retention (>10 years/85 °C) and endurance (>10 cycles). The exceptional performance is attributed to the presence of thin tetragonal phase layers within the thick ferroelectric layers, which decreased the switching barrier in the nanolaminate films. Further, we verified phase crystallization via a detailed analysis of high-resolution transmission electron microscopy images. The improved switching propagation in the nanolaminate films was confirmed through switching speed measurements and theoretical models. Furthermore, we addressed pinching issues by precisely controlling the Hf/Zr ratio and O treatment. The initial imprint and retention characteristics were improved by interfacial engineering. Moreover, by reducing the thickness, we have achieved reliable operation at 1.0 V with a 5.5 nm-thick device while maintaining high retention and endurance. This study is a significant step toward the realization of the longstanding problem of ferroelectric random access memory operation voltage with respect to endurance and retention characteristics.
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http://dx.doi.org/10.1021/acsami.4c08641 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra 08193, Spain.
Nanolaminates based on ferroelectric polycrystalline doped HfO have gained interest because those compounds show enhanced functional properties. Here, we achieve coexisting improvement of remanent polarization and dielectric permittivity in wake-up-free epitaxial HfZrO/HfO nanolaminates with different numbers of HfO nanolayers if compared with HfZrO single films of equivalent thickness or other reported polycrystalline nanolaminates. Comprehensive structural characterization reveals that the origin of the enhancement must be the larger amount of the orthorhombic phase in the nanolaminates.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China.
ACS Appl Mater Interfaces
October 2024
Center for Single Atom-based Semiconductor Device and the Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Korea.
Hafnia thin films are known to demonstrate excellent performance with strong ferroelectricity and high scalability, making them promising candidates for CMOS-compatible materials. However, the reliability of ferroelectric devices must be further improved. This study developed a HfZrO ferroelectric capacitor with a nanolaminate structure that operated at remarkably low voltages, demonstrating excellent retention (>10 years/85 °C) and endurance (>10 cycles).
View Article and Find Full Text PDFThe MAX phase represents a diverse class of nanolaminate materials with intriguing properties that have received incredible global research attention because they bridge the divide separating metals and ceramics. Despite the numerous potential applications of MAX phases, their complex structure leads to a scarcity of readily accessible pure MAX phases. As a result, in-depth research on synthesis methods, characteristics, and structure is frequently needed for appropriate application.
View Article and Find Full Text PDFNat Commun
August 2024
Key Laboratory of Pressure Systems and Safety, Ministry of Education, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Fatigue failure is invariably the most crucial failure mode for metallic structural components. Most microstructural strategies for enhancing fatigue resistance are effective in suppressing either crack initiation or propagation, but often do not work for both synergistically. Here, we demonstrate that this challenge can be overcome by architecting a gradient structure featuring a surface layer of nacre-like nanolaminates followed by multi-variant twinned structure in pure titanium.
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