Key Takeaways & Executive Findings
- •• • Endurance exceeding 10^12 cycles is achievable through ordered defect architectures, addressing the reliability bottleneck for non-volatile memory applications. • • Ultrahigh remanent polarization in Ce-doped HfO2 thin films is realized via strain engineering, demonstrating the effectiveness of strain-mediated defect control. • • Interface engineering in Hf0.5Zr0.5O2 ultrathin films yields fatigue-free ferroelectricity, enabling stable operation over extended cycling. • • Reducing coercive field and improving endurance in epitaxial Hf0.5Zr0.5O2 films is achieved via novel interface layer approaches, enhancing switching efficiency.
Abstract
Hafnia-based ferroelectrics exhibit a distinctive reverse size effect and exceptional scalability, positioning them as critical candidates for CMOS-compatible non-volatile memory and ferroelectric transistors, with substantial promise for advancing hardware acceleration in artificial intelligence and large-data storage technologies. However, their practical deployment is constrained by a longstanding dilemma: the difficulty in simultaneously stabilizing metastable polar phases and ensuring long-term reliability under the high electric fields required for polarization switching. This review reinterprets this challenge through the lens of defect physics and advocates a paradigm shift from stochastic, disorder-mediated defect incorporation toward ordered, multiscale defect engineering. We systematically discuss the collective influence of point defects, line defects, planar defects, and defect-coupled structures on the phase stability, switching kinetics, and failure mechanisms in hafnia-based ferroelectrics. Controlling oxygen-vacancy states, engineering dopants via Fermi-level and chemical pressure, deploying periodic dislocation arrays, designing topological domain walls, functionalizing interfaces, and leveraging flexoelectric strain gradients constitute the core strategic toolkit. Through such ordered defect architectures, scalable performance metrics, including high remanent polarization, low coercive field, fast switching speed, and endurance exceeding 10^12 cycles, become attainable. These approaches establish a set of design principles for next-generation low-power, high-reliability ferroelectric electronics.
1. Introduction
The exponential growth of data in artificial intelligence, the Internet of Things, and cloud computing has intensified the demand for high-speed, high-density, and non-volatile memory technologies. The traditional von Neumann architecture suffers from a 'memory wall' bottleneck, where the performance gap between the central processing unit and memory leads to severe bandwidth limitations and reduced computational efficiency. Ferroelectric memories, leveraging electric-field-driven switching, offer superior energy efficiency compared to magnetoresistive, phase-change, and resistive switching memories. Among ferroelectric materials, hafnia-based compounds stand out due to their reverse size effect, where ferroelectricity is preserved or even enhanced at the nanoscale, and their compatibility with CMOS processing. However, commercialization is hindered by the trade-off between thermodynamic phase stability and kinetic reliability under high electric fields.
This review addresses this bottleneck by proposing a paradigm shift from stochastic defect incorporation to ordered, multiscale defect engineering. By systematically controlling point defects, line defects, planar defects, and defect-coupled structures, it is possible to stabilize metastable polar phases and enhance switching kinetics simultaneously. The strategic toolkit includes oxygen-vacancy control, dopant engineering via Fermi-level and chemical pressure, periodic dislocation arrays, topological domain walls, interface functionalization, and flexoelectric strain gradients. These approaches enable scalable performance metrics, such as high remanent polarization, low coercive field, fast switching speed, and endurance exceeding 10^12 cycles, establishing design principles for next-generation low-power, high-reliability ferroelectric electronics.
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Chaoqun Jiang, Jinfan Yang, Xiangdong Xu, Shiyao Sun, Yong Xu, Zhongzhong Luo (2026). Multiscale Ordered Defect Design for Tailoring Ferroelectric Phase Stability and Switching Kinetics in Hafnia Ferroelectrics. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-026-4257-y
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Frequently Asked Questions
What are the specific mechanisms by which ordered defect architectures improve endurance beyond 10^12 cycles in hafnia-based ferroelectrics?
Ordered defect architectures, such as periodic dislocation arrays and engineered interfaces, mitigate the stochastic generation of oxygen vacancies and charge trapping, which are primary causes of fatigue and imprint. By controlling defect distribution and valence states, these architectures reduce domain wall pinning and internal bias fields, thereby enhancing endurance to exceed 10^12 cycles.
How does strain engineering via Ce doping achieve ultrahigh remanent polarization in HfO2 thin films, and what are the reported values?
Ce doping introduces chemical pressure and modifies the oxygen vacancy landscape, stabilizing the ferroelectric orthorhombic phase. Combined with epitaxial strain, this approach enhances remanent polarization to ultrahigh levels, as reported in the literature (e.g., Li et al., Sci China Mater, 2025, 68: 2792–2798). The exact value is not specified in the provided text, but the paper indicates 'ultrahigh' remanent polarization.
What is the trade-off between polarization enhancement and reliability in interfacial layer engineering of Zr-doped HfO2 films, and how is it managed?
Interfacial layer engineering can enhance polarization by stabilizing the ferroelectric phase, but it may introduce defects that degrade reliability. The trade-off is managed by optimizing the interface composition and thickness to balance polarization enhancement with endurance and retention, as discussed in Yang et al. (ACS Appl Mater Interfaces, 2025, 17: 59864–59872).
Can the proposed ordered defect engineering be integrated into existing CMOS fabrication processes without significant cost increases?
The techniques involved, such as dopant engineering and interface layer deposition, are compatible with standard CMOS processing. However, precise control of defect ordering may require additional annealing or deposition steps, potentially increasing process complexity. The paper suggests that these approaches are scalable, but cost implications depend on specific integration schemes.
What are the primary failure mechanisms in hafnia-based ferroelectrics under high electric fields, and how does ordered defect design mitigate them?
Primary failure mechanisms include oxygen vacancy migration, charge trapping at interfaces, and domain wall pinning, leading to fatigue, imprint, and breakdown. Ordered defect design, such as controlling oxygen vacancy states and engineering interfaces, reduces these effects by stabilizing the domain structure and minimizing defect-induced internal fields, thereby improving reliability.
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