Electric‐Field‐Induced Ferroelectricity in 5%Y‐doped Hf0.5Zr0.5O2: Transformation from the Paraelectric Tetragonal Phase to the Ferroelectric Orthorhombic Phase

Shiraishi, Takashi; Tashiro, Yuki; Mimura, Takanori; Kiguchi, Takanori; Shiraishi, Takahisa; Konnno, Toyohiko J.; Sakata, Osami; Funakubo, Hiroshi

doi:10.1002/pssr.202170023

Cited by 2 publications

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“…As the Curie temperature is in the range of 350–550 °C, HfO 2 films are expected to consist mainly of that orthorhombic phase, which has been recently confirmed, demonstrating that the antiferroelectric-like behavior is driven by ferroelastic switching (90°-domain wall motion). However, for very high doping concentrations, the supercooled tetragonal phase may be preserved. , …”

Section: Introductionmentioning

confidence: 99%

“…However, for very high doping concentrations, the supercooled tetragonal phase may be preserved. 21,22 While recent studies have investigated the influence of doping element 23 and substrate layer 24 on the microstructural composition of the film, a deeper understanding of the crystallization process as well as annealing temperature influences is still elusive. Here, we investigate the influence of different annealing temperatures on the microstructure of Sidoped HfO 2 (HSO) films grown on TiN and SiO 2 layers.…”

Section: ■ Introductionmentioning

confidence: 99%

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Influence of Annealing Temperature on the Structural and Electrical Properties of Si-Doped Ferroelectric Hafnium Oxide

Lederer

Bagul

Lehninger

et al. 2021

ACS Appl. Electron. Mater.

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The ferroelectric properties of hafnium oxide films are strongly influenced by the crystallization process due to the interaction of thermodynamics, kinetics, and mechanical stress. In this work, the influence of annealing temperature on the crystallographic properties and microstructure of Si-doped hafnium oxide thin films as well as their ferroelectric properties are investigated by X-ray diffraction, transmission Kikuchi diffraction, and electrical characterization. The findings reveal the emergence of a [100] and [110] out-of-plane texture for metal−ferroelectric− metal (MFM) and metal−ferroelectric−insulator−semiconductor (MFIS) capacitor structures with increasing annealing temperature, respectively. In combination with observed stress relaxation at higher temperatures and the evolution of the wake-up behavior, insights into the crystallization process and the influence of the interplay of microstructure and stress on the ferroelectric properties of hafnium oxide thin films are given.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Influence of Annealing Temperature on the Structural and Electrical Properties of Si-Doped Ferroelectric Hafnium Oxide

Lederer

Bagul

Lehninger

et al. 2021

ACS Appl. Electron. Mater.

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“…[ 28 ] ITO (Sn‐doped In 2 O 3 ) has the bixbyite structure with a cubic lattice parameter of 10.12 Å, close to twice those of the hafnia polymorphs and YSZ (≈5.15 Å), and thus it can potentially match their fluorite structure. In the case of YSZ(111), the films studied were Hf 1‐x Zr x O 2 , [ 26,29 ] Y‐doped HfO 2 , [ 30–36 ] Y‐doped Hf 1‐x Zr x O 2 , [ 37,38 ] and Ce‐doped HfO 2 , [ 39 ] being TiN the buffer layer in only one case, [ 26 ] and ITO(111) in the rest. These hafnia films crystallize totally or partially in the orthorhombic polymorph.…”

Section: Introductionmentioning

confidence: 99%

“…The maximum values of remanent polarization are typically in the range of 5–15 μC cm −2 , and slightly higher in Ce‐doped HfO 2 [ 39 ] and Y‐doped Hf 1‐x Zr x O 2 . [ 37,38 ]…”

Section: Introductionmentioning

confidence: 99%

Epitaxy‐Driven Ferroelectric/Non‐Ferroelectric Polymorph Selection in an All‐Fluorite System

Barriuso,

Jiménez,

Langenberg

et al. 2024

Adv Elect Materials

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Films of ferroelectric hafnia have hitherto been deposited on electrodes with a non‐fluorite crystal structure. As a result, they are polycrystalline, contain fractions of non‐ferroelectric polymorphs or have poor crystal quality. Here, a strategy that circumvents all these limitations is shown. Seven nanometers‐thick epitaxial Hf0.5Zr0.5O2 (HZO) films are deposited directly on yttria‐stabilized zirconia (YSZ) single‐crystals. The fluorite structure of the whole system enables coherent epitaxy, while the substrate orientation induces polymorph‐selective growth, being the HZO films orthorhombic on YSZ(111) and monoclinic on YSZ(001). Besides, the YSZ substrate can play the role of a buried floating electrode under the appropriate measuring conditions (temperature and frequency) thanks to its thermally‐activated oxygen conductivity. Indeed, out‐of‐plane ferroelectric switching is confirmed in the orthorhombic HZO samples at 185 °C and 0.01 Hz frequency. This original approach avoids the need to deposit conducting bottom layers, allowing high‐quality orthorhombic hafnia to be obtained directly on the substrate and its ferroelectric nature to be studied. Moreover, it constitutes a case of ion‐driven ferroelectric switching, and thus gives support to the recently proposed relationship between ionic conductivity, and ferroelectricity in fluorite systems.

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Electric‐Field‐Induced Ferroelectricity in 5%Y‐doped Hf_0.5Zr_0.5O₂: Transformation from the Paraelectric Tetragonal Phase to the Ferroelectric Orthorhombic Phase

Cited by 2 publications

References 0 publications

Influence of Annealing Temperature on the Structural and Electrical Properties of Si-Doped Ferroelectric Hafnium Oxide

Influence of Annealing Temperature on the Structural and Electrical Properties of Si-Doped Ferroelectric Hafnium Oxide

Epitaxy‐Driven Ferroelectric/Non‐Ferroelectric Polymorph Selection in an All‐Fluorite System

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