Ferroelectric ZrO<sub>2</sub> phases from infrared spectroscopy

El Boutaybi, Ali; Cervasio, Rebecca; Degezelle, Alban; Maroutian, Thomas; Brubach, Jean-Blaise; Demange, Valérie; Largeau, Ludovic; Verseils, Marine; Matzen, Sylvia; Agnus, Guillaume; Vivien, Laurent; Karamanis, Panagiotis; Rérat, Michel; Roy, Pascale; Lecoeur, Philippe

doi:10.1039/d3tc01985c

Cited by 4 publications

(2 citation statements)

References 96 publications

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“…Not only does this allow us to validate the simulation parameters, but the comparison between parent compounds and HZO provides the first assignment of each band vibration. Moreover, our results are in very good agreement with the previous theoretical work carried out by El Boutaybi et al for the m-, t-, and o-phases of zirconia and Materlik et al…”

Section: Density Functional Theory Resultssupporting

confidence: 93%

Quantification of Crystalline Phases in Hf_0.5Zr_0.5O₂ Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Cervasio,

Amzallag,

Verseils

et al. 2024

ACS Appl. Mater. Interfaces

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In the quest for thinner and more efficient ferroelectric devices, Hf 0.5 Zr 0.5 O 2 (HZO) has emerged as a potential ultrathin and lead-free ferroelectric material. Indeed, when deposited on a TiN electrode, 1−25 nm thick HZO exhibits excellent ferroelectricity capability, allowing the prospective miniaturization of capacitors and transistor devices. To investigate the origin of ferroelectricity in HZO thin films, we conducted a farinfrared (FIR) spectroscopic study on 5 HZO films with thicknesses ranging from 10 to 52 nm, both within and out of the ferroelectric thickness range where ferroelectric properties are observed. Based on X-ray diffraction, these HZO films are estimated to contain various proportions of monoclinic (m-), tetragonal (t-), and polar orthorhombic (polar o-) phases, while only the 11, 17, and 21 nm thick are expected to include a higher amount of polar o-phase. We coupled the HZO infrared measurements with DFT simulations for these m-, t-, and polar o-crystallographic structures. The approach used was based on the supercell method, which combines all possible Hf/Zr mixed atomic sites in the solid solution. The excellent agreement between measured and simulated spectra allows assigning most bands and provides infrared signatures for the various HZO structures, including the polar orthorhombic form. Beyond pure assignment of bands, the DFT IR spectra averaging using a mix of different compositions (e.g., 70% polar o-phase +30% m-phase) of HZO DFT crystal phases allows quantification of the percentage of different structures inside the different HZO film thicknesses. Regarding the experimental data analysis, we used the spectroscopic data to perform a Kramers−Kronig constrained variational fit to extract the optical functions of the films using a Drude−Lorentzbased model. We found that the ferroelectric films could be described using a set of about 7 oscillators, which results in static dielectric constants in good agreement with theoretical values and previously reported ones for HfO 2 -doped ferroelectric films.

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Section: Density Functional Theory Resultssupporting

confidence: 93%

Quantification of Crystalline Phases in Hf_0.5Zr_0.5O₂ Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Cervasio,

Amzallag,

Verseils

et al. 2024

ACS Appl. Mater. Interfaces

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“…18 The ferroelectricity of the ZrO 2 thin film was experimentally revealed in a Pt/ZrO 2 (6.1− 19.6 nm)/Pt structure. 11 Further investigations revealed that the ferroelectricity of ZrO 2 films can be influenced by many factors, such as doping, 19−21 film thickness, 22,23 epitaxial strain, 24 interfacial layers, 25 electrode material, 26 and oxygen source dose time. 27 It was found that the macroscopic ferroelectric responses can be ascribed to the formation of the orthorhombic or rhombohedral (r) phase in the ZrO 2 films.…”

Section: Introductionmentioning

confidence: 99%

Pure ZrO₂ Ferroelectric Thin Film for Nonvolatile Memory and Neural Network Computing

Wang,

Guan,

Wang

et al. 2024

ACS Appl. Mater. Interfaces

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The recent discovery of ferroelectricity in pure ZrO2 has drawn much attention, but the information storage and processing performances of ferroelectric ZrO2-based nonvolatile devices remain open for further exploration. Here, a ZrO2 (∼8 nm)-based ferroelectric capacitor using RuO2 oxide electrodes is fabricated, and the ferroelectric orthorhombic phase evolution under electric field cycling is studied. A ferroelectric remnant polarization (2P r) of >30 μC/cm2, leakage current density of ∼2.79 × 10–8 A/cm2 at 1 MV/cm, and estimated polarization retention of >10 years are achieved. When the ferroelectric capacitor is connected with a transistor, a memory window of ∼0.8 V and eight distinct states can be obtained in such a ferroelectric field-effect transistor (FeFET). Through the conductance manipulation of the FeFET, a high object image recognition accuracy of ∼93.32% is achieved on the basis of the CIFAR-10 dataset in the convolutional neural network (CNN) simulation, which is close to the result of ∼94.20% obtained by floating-point-based CNN software. These results demonstrate the potential of ferroelectric ZrO2 devices for nonvolatile memory and artificial neural network computing.

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Transistors with ferroelectric ZrXAl1−XOY crystallized by ZnO growth for multi-level memory and neuromorphic computing

Islam,

Ali,

Park

et al. 2024

Commun Mater

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Ferroelectric (FE) field-effect transistors are interesting for their non-destructive readout characteristic and energy efficiency but are difficult to integrate on silicon platforms. Here, FE ZrXAl1−XOY (ZAO) is demonstrated by compressive strain in contact with ZnO. The metal-ferroelectric-semiconductor-metal capacitor exhibits a substantial remnant polarization of 15.2 µC cm−2, along with a bowknot-like anti-clockwise hysteresis in the capacitance curves. The FE-ZAO gated ZnO thin-film transistor presents a large memory window (3.84 V), low subthreshold swing (55 mV dec−1), high ION/IOFF ratio (≈108), and low off-state current (≈1 pA). The grazing incidence X-ray diffraction and scanning transmission electron microscopy analyses reveal the ferroelectric rhombohedral phase (space group R3m) in the nanocrystal ZAO, containing an angle of ≈71.7° between the [111] and [11-1] directions with d111-spacing of 3.037 Å and d11-1-spacing of 2.927 Å. Finally, the memory and neuromorphic applications are analyzed by demonstrating multi-level memory and synaptic weight performance with a high learning accuracy of 91.82%.

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Ferroelectric ZrO₂ phases from infrared spectroscopy

Abstract: We investigate ferroelectric thin films of ZrO$_2$ experimentally and theoretically using infrared (IR) absorption spectroscopy coupled with density functional theory (DFT) calculations. The IR absorbance is measured using IR synchrotron...

Cited by 4 publications

References 96 publications

Quantification of Crystalline Phases in Hf_0.5Zr_0.5O₂ Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Quantification of Crystalline Phases in Hf_0.5Zr_0.5O₂ Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Pure ZrO₂ Ferroelectric Thin Film for Nonvolatile Memory and Neural Network Computing

Transistors with ferroelectric ZrXAl1−XOY crystallized by ZnO growth for multi-level memory and neuromorphic computing

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Ferroelectric ZrO2 phases from infrared spectroscopy

Abstract: We investigate ferroelectric thin films of ZrO$_2$ experimentally and theoretically using infrared (IR) absorption spectroscopy coupled with density functional theory (DFT) calculations. The IR absorbance is measured using IR synchrotron...

Cited by 4 publications

References 96 publications

Quantification of Crystalline Phases in Hf0.5Zr0.5O2 Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Quantification of Crystalline Phases in Hf0.5Zr0.5O2 Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Pure ZrO2 Ferroelectric Thin Film for Nonvolatile Memory and Neural Network Computing

Transistors with ferroelectric ZrXAl1−XOY crystallized by ZnO growth for multi-level memory and neuromorphic computing

Contact Info

Product

Resources

About

Ferroelectric ZrO₂ phases from infrared spectroscopy

Quantification of Crystalline Phases in Hf_0.5Zr_0.5O₂ Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Quantification of Crystalline Phases in Hf_0.5Zr_0.5O₂ Thin Films through Complementary Infrared Spectroscopy and Ab Initio Supercell Simulations

Pure ZrO₂ Ferroelectric Thin Film for Nonvolatile Memory and Neural Network Computing