Epitaxial Ferroelectric La-Doped Hf0.5Zr0.5O2 Thin Films

Song, Tingfeng; Bachelet, Romain; Saint-Girons, Guillaume; Solanas, Raúl; Fina, Ignasi; Barrera, Florencio Sánchez

doi:10.1021/acsaelm.0c00560

Cited by 59 publications

(50 citation statements)

References 55 publications

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“…[ 30,31 ] The I‐V characteristics are presented in Figure 3c. The maximum leakage current density observed is around 10 −6 A cm −2 even at an applied voltage of 22 V, which is comparable with previously reported values in HfO 2 ‐based materials prepared by PLD, [ 32 ] ALD, [ 33 ] and sputtering. [ 34 ] Notably, the leakage current is even lower than those from the other reports (e.g., ALD, [ 35,36 ] PLD, [ 29 ] sputtering [ 37 ] ).…”

Section: Resultssupporting

confidence: 90%

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO₂ Films

Samanta

Anoop

Joh

et al. 2021

Adv Materials Inter

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Ferroelectricity in HfO2 thin films can be utilized for fast, power‐efficient, and highly scalable non‐volatile memories. However, the required wake‐up process for inducing ferroelectricity/ achieving higher polarization is one of the major hurdles that hinder HfO2‐based thin films from developing reliable electronic devices. The wake‐up effect is believed to originate from i) phase transformation from non‐ferroelectric to ferroelectric, ii) movement of defect entities (mainly oxygen vacancy defects) near the film‐electrode interface, and iii) heterogeneity of the electrode interfaces. In the present study, an experimental strategy is designed to overcome these sources of the wake‐up process. A multi‐step deposition and annealing process is carried out to induce wake‐up‐free ferroelectricity in Yttrium doped HfO2 (Y:HfO2) thin film directly grown on Si‐substrate. Furnace annealing is utilized instead of the standard rapid thermal annealing process to reduce the oxygen deficiencies and stimulate the direct growth of the polar Y:HfO2. The oxygen‐vacancy‐related defects are found to be the dominating source of wake‐up effect in Y‐doped HfO2 films. The step‐wise deposition and annealing in the oxygen atmosphere facilitate direct growth of the polar phase, reduce the oxygen vacancies, and induce wake‐up‐free ferroelectricity in Y:HfO2.

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Section: Resultssupporting

confidence: 90%

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO₂ Films

Samanta

Anoop

Joh

et al. 2021

Adv Materials Inter

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“…Table I summarizes the ferroelectric properties of epitaxial films of doped HfO2. Among the chemical compositions investigated, the highest remanent polarization of around 30-34 µC/cm 2 is reported for Hf0.5Zr0.5O2, 51,66,116 La-doped Hf0.5Zr0.5O2 63 and Si-doped HfO2 films. 50 High endurance of up to 10 11 and 5x10 10 cycles has been measured for Hf0.5Zr0.5O2 116 and La-doped Hf0.5Zr0.5O2 63 films, respectively.…”

Section: Endurance and Retentionmentioning

confidence: 93%

“…The same dependence of coercive field on thickness was observed for epitaxial HZO films on Si(001) 85 and La-doped HZO films on STO(001) and Si(001). 63 It signals that crystal grain size along the out-of-plane direction is not smaller than the film thickness. In contrast, Ec does not change significantly with thickness in epitaxial YHO films obtained by annealing of amorphous layers, 80,91 or usually in polycrystalline HfO2 films, 100 but yes (showing Ec  t -2/3 ) for polycrystalline films thinner than around 30 nm and grains spanning across the entire thickness.…”

Section: Dependence Of Pr and Ec On Thicknessmentioning

confidence: 99%

Epitaxial Ferroelectric HfO₂ Films: Growth, Properties, and Devices

Fina

Sánchez

2021

ACS Appl. Electron. Mater.

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About ten years after ferroelectricity was first reported in doped HfO2 polycrystalline films, there is tremendous interest in this material and ferroelectric oxides are once again in the spotlight of the memories industry. Great efforts are being made to understand and control ferroelectric properties. Epitaxial films, which have fewer defects and a more controlled microstructure than polycrystalline films, can be very useful for this purpose. Epitaxial films of ferroelectric HfO2 have been much less investigated, but after the first report in 2015 significant progress has been achieved. This review summarizes and discusses the main advances on epitaxial HfO2, considering growth, study of structural and ferroelectric properties, identification of the ferroelectric phase, and fabrication of devices. We hope this review will help to researchers investigating epitaxial HfO2. It can also help extend the interest of the ferroelectric HfO2 community, now basically focused on polycrystalline samples, to epitaxial films.

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“…(1-x)HfO 2 -xZrO 2 /Si(100) [75] HZO/LSMO/(001)STO [139] [38] HZO/LSMO/STO/Si [55] 800 0.1 7.7 34 No…”

Section: Substrate And/or Bottom Electrode Selectionmentioning

confidence: 99%

An Overview of Ferroelectric Hafnia and Epitaxial Growth

Cao

Shi

Zhu

et al. 2021

Physica Rapid Research Ltrs

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Hafnia thin films have been under intensive research during the past few years due to its robust ferroelectricity under very thin limit and good compatibility with silicon. The polar crystal structure critical to ferroelectricity in hafnia thin films is metastable, and is generally obtained in polycrystalline thin films, coexisting with other nonpolar phases. Recently, much attention has been focused on epitaxial ferroelectric hafnia thin films to get rid of the nonpolar phases, to investigate the more intrinsic factors to ferroelectricity, and its potential applications. Herein, recent progress on the growth of epitaxial hafnia thin films is reviewed. The epitaxial growth mechanism is explored, in particular, the interface matching, phase stability under temperature and oxygen pressure, followed by discussions on thickness dependency of ferroelectricity, and wake-up effect in hafnia. Finally, an outlook on ferroelectric hafnia both on fundamental studies and future applications is discussed.

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Epitaxial Ferroelectric La-Doped Hf_0.5Zr_0.5O₂ Thin Films

Cited by 59 publications

References 55 publications

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO₂ Films

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO₂ Films

Epitaxial Ferroelectric HfO₂ Films: Growth, Properties, and Devices

An Overview of Ferroelectric Hafnia and Epitaxial Growth

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Epitaxial Ferroelectric La-Doped Hf0.5Zr0.5O2 Thin Films

Cited by 59 publications

References 55 publications

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO2 Films

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO2 Films

Epitaxial Ferroelectric HfO2 Films: Growth, Properties, and Devices

An Overview of Ferroelectric Hafnia and Epitaxial Growth

Contact Info

Product

Resources

About

Epitaxial Ferroelectric La-Doped Hf_0.5Zr_0.5O₂ Thin Films

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO₂ Films

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO₂ Films

Epitaxial Ferroelectric HfO₂ Films: Growth, Properties, and Devices