Séminaire – Manisha Bansal

Le jeudi 12 novembre à 11h (auditorium TRT), nous aurons le plaisir d’accueillir Manisha Bansal (Department of Materials Science and Metallurgy, University of Cambridge) qui présentera un séminaire au laboratoire.

Titre:

“Strategies for Ultrahigh Endurance in Ferroelectric Hafnia-Based Thin Films Via Novel Device Engineering Routes”

Abstract:

Ferroelectric hafnia-based thin films are a leading candidate for next-generation non-volatile memory and neuromorphic computing, owing to their CMOS compatibility, scalability to nanometre thicknesses, and robust ferroelectricity. Despite this promise, practical deployment has long been constrained by limited endurance, with most devices exhibiting wake-up, imprint, and hard dielectric breakdown well within the cycle counts required for embedded memory and high-cycle neuromorphic applications. The endurance bottleneck is widely linked to the progressive accumulation of oxygen vacancies at the interfaces and within the ferroelectric film, which act as preferential sites for charge trapping, local phase instability, and eventual breakdown.

In this talk, I will show two complementary model systems in which ultrahigh endurance, exceeding 10^11 bipolar switching cycles with minimal fatigue, is achieved in hafnia-based thin films by controlling oxygen vacancy behaviour through novel engineering routes. In the first case, epitaxial hafnia-based films grown directly on silicon substrates are used to isolate how structural domain boundaries influence oxygen vacancy migration and clustering. In the second case, replacing conventional metal bottom electrodes with wafer-scale monolayer graphene electrodes show exceptional ferroelectric properties including ultralow coercive field (EC < 1.5 MV/cm) and ultrahigh endurance (>10^11 cycles) with nearly no fatigue in hafnia-based ferroelectric thin films. Further, electrical measurements are combined with structural and chemical analysis to correlate device performance with the underlying microstructure and interfacial chemistry.

These results indicate that controlling oxygen vacancy distribution at structural boundaries and interfaces, whether through film architecture or electrode choice, is essential for high reliability of hafnia-based ferroelectric devices. These strategies offer a route towards fatigue-free, high-endurance ferroelectric memory across a range of device platforms, including silicon and emerging two-dimensional material integration, compatible with mainstream semiconductor manufacturing.

References

1. Nukala, P., Reversible oxygen migration and phase transitions in hafnia-based ferroelectric devices. Science, 372(6542), 630-635 (2021).
2. Levlev, A. V. et al. Non-conventionalmechanism of ferroelectric fatigue via cation migration. Nature communications, 10(1), 3064 (2019).
3. Zhou, C. et al. Fatigue-free ferroelectricity in Hf0.5Zr0.5O2 ultrathin films via interfacial design. Nature Communications, 16(1), 7593 (2025).
4. Zhao, J., et al. High-temperature memristors enabled by interfacial engineering. Science, 392(6799), 771-779 (2026).
5. Lin, C. Y., et al. Integration of freestanding hafnium zirconium oxide membranes into two-dimensional transistors as a high-κ ferroelectric dielectric. Nature Electronics, 8(7), 560-570 (2025).