Evolution of ferroelectric HfO2 in ultrathin region down to 3 nm

Tian, Xuan; Shibayama, Shigehisa; Nishimura, Tomonori; Yajima, Takeaki; Migita, Shinji; Toriumi, Akira

doi:10.1063/1.5017094

Cited by 196 publications

(135 citation statements)

References 39 publications

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“…Although there is still an uncertainty depending on the assumed material structure and an adopted method to calculate it, it is typically several nm (several to ten unit cells) for the perovskite ferroelectrics. Fluorite‐based ferroelectrics are less studied in this regard, but they may have a similar limit …”

Section: Stabilization Of Nc By Scaling Device Dimensionsmentioning

confidence: 99%

Modeling of Negative Capacitance in Ferroelectric Thin Films

et al. 2019

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Section: Stabilization Of Nc By Scaling Device Dimensionsmentioning

confidence: 99%

Modeling of Negative Capacitance in Ferroelectric Thin Films

et al. 2019

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“…The relative amount of the orthorhombic phase and the ferroelectric properties depend on the annealing conditions and film thickness. 3,[6][7][8][9][10][11][12][13] The ferroelectric orthorhombic phase can be also stabilized in epitaxial films. [14][15][16][17][18][19][20][21] In epitaxial films, the orthorhombic phase is generally formed during deposition at high temperature, without need of annealing.…”

Section: Introductionmentioning

confidence: 99%

Growth Window of Ferroelectric Epitaxial Hf_0.5Zr_0.5O₂ Thin Films

Lyu

Fina

Solanas

et al. 2019

ACS Appl. Electron. Mater.

208

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The metastable orthorhombic phase of hafnia is generally obtained in polycrystalline films, whereas in epitaxial films its formation has been much less investigated. We have grown Hf0.5Zr0.5O2 films by pulsed laser deposition and the growth window (temperature and oxygen pressure during deposition, and film thickness) for epitaxial stabilization of the ferroelectric phase is mapped. The remnant ferroelectric polarization, up to 24 C/cm 2 , depends on the amount of orthorhombic phase and interplanar spacing and increases with temperature and pressure for a fixed film thickness. The leakage current decreases with an increase in thickness or temperature, or when decreasing oxygen pressure. The coercive electric field (EC) depends on thickness (t) according the EC -t -2/3 scaling, which is observed by the first time in ferroelectric hafnia, and the scaling extends to thickness down to around 5 nm. The proven ability to tailor functional properties of high quality epitaxial ferroelectric Hf0.5Zr0.5O2 films paves the way toward understanding their ferroelectric properties and prototyping devices.

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“…As proved by additional simulations (not reported here), further decreasing the Y:HfO 2 film thickness down to 5 nm can enhance the SHG intensity by an order of magnitude. Indeed, ferroelectricity has been reported in a 3 nm thick HfO 2 thin film on silicon, 32 which ensures further decreasing of the film thickness and enhancing of the SHG efficiency, toward a large-scale CMOS integration of nonlinear photonic light sources.…”

Section: Acs Nanomentioning

confidence: 99%

Enhanced Second Harmonic Generation from Ferroelectric HfO₂-Based Hybrid Metasurfaces

Qin

Huang

et al. 2019

ACS Nano

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Integrated nonlinear metasurfaces leading to high-efficiency optical second harmonic generation (SHG) are highly desirable for optical sensing, imaging, and quantum photonic systems. Compared to traditional metal-only metasurfaces, their hybrid counterparts, where a noncentrosymmetric nonlinear photonic material is incorporated in the near-field of a metasurface, can significantly boost SHG efficiency. However, it is difficult to integrate such devices on-chip due to material incompatibilities, thickness scaling challenges, and the narrow band gaps of nonlinear optical materials. Here, we demonstrate significantly enhanced SHG in on-chip integrated metasurfaces by using nanometer thin films of ferroelectric Y:HfO2. This material has the merit of CMOS compatibility, ultraviolet transparency up to 250 nm, and significant scalability down to sub-10 nm when deposited on silicon. We observe a 20-fold magnitude enhancement of the SHG intensity from the hybrid metasurface compared to a bare ferroelectric HfO2 thin film. Moreover, a 3-fold SHG enhancement is observed from the hybrid metasurface compared to a control structure using nonferroelectric HfO2, demonstrating a major contribution to the SHG signal from ferroelectric Y:HfO2. The effective second-order nonlinear optical coefficient χ(2) of Y:HfO2 is determined to be 6.0 ± 0.5 pm/V, which is comparable to other complex nonlinear photonic oxide materials. Our work provides a general pathway to build an efficient on-chip nanophotonic nonlinear light source for SHG using ferroelectric HfO2 thin films.

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Evolution of ferroelectric HfO2 in ultrathin region down to 3 nm

Cited by 196 publications

References 39 publications

Modeling of Negative Capacitance in Ferroelectric Thin Films

Modeling of Negative Capacitance in Ferroelectric Thin Films

Growth Window of Ferroelectric Epitaxial Hf_0.5Zr_0.5O₂ Thin Films

Enhanced Second Harmonic Generation from Ferroelectric HfO₂-Based Hybrid Metasurfaces

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Evolution of ferroelectric HfO2 in ultrathin region down to 3 nm

Cited by 196 publications

References 39 publications

Modeling of Negative Capacitance in Ferroelectric Thin Films

Modeling of Negative Capacitance in Ferroelectric Thin Films

Growth Window of Ferroelectric Epitaxial Hf0.5Zr0.5O2 Thin Films

Enhanced Second Harmonic Generation from Ferroelectric HfO2-Based Hybrid Metasurfaces

Contact Info

Product

Resources

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Growth Window of Ferroelectric Epitaxial Hf_0.5Zr_0.5O₂ Thin Films

Enhanced Second Harmonic Generation from Ferroelectric HfO₂-Based Hybrid Metasurfaces