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Cited by 19Ferroelectric and Piezoelectric MaterialsFerroelectric and Negative Capacitance DevicesMultiferroics and related materials

The other model antiferroelectric: PbHfO3 thin films from ALD precursors

Open access
Hanrahan, Brendan, Milesi-Brault, Cosme, Leff, Asher, Payne, Alexis, Liu, Shi, Guennou, Mael, Strnad, Nicholas·2021·APL Materials
DOI 10.1063/5.0035730
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Abstract

Antiferroelectric PbHfO3 is grown from atomic layer deposition precursors lead bis(dimethylaminomethylpropanolate) and tetrakis dimethylamino hafnium with H2O and O3 oxidizers in thicknesses from 20 nm to 200 nm at a substrate temperature of 250 °C. X-ray analysis shows an as-grown crystalline PbO phase that diffuses into an amorphous HfO2 matrix upon annealing to form a randomly oriented, orthorhombic PbHfO3 thin film. Electrical characterization reveals characteristic double hysteresis loops with maximum polarizations of around 30 µC/cm2 and transition fields of 350 kV/cm–500 kV/cm depending on the thickness. Temperature-dependent permittivity and polarization testing show a phase transition at 185 °C, most probably to the paraelectric phase, but give no clear evidence for the intermediate phase known from bulk PbHfO3. The energy storage density for the films reaches 16 J/cm3 at 2 MV/cm. A dielectric tunability of 221% is available within 1 V for the thinnest film. These results highlight the unique spectrum of properties available for thin film perovskite antiferroelectrics.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper reports atomic layer deposition of antiferroelectric PbHfO₃ thin films from Pb(DMAMP)₂ and TDMAH precursors with H₂O/O₃ oxidizers, forming orthorhombic PHO after annealing. It shows characteristic double hysteresis, high energy storage density, and a dielectric transition at 185 °C, while finding no clear evidence for the intermediate phase known in bulk PHO.

Key findings

  • ALD-grown PHO films from 20 nm to 200 nm at 250 °C crystallize by interdiffusion of as-grown crystalline PbO into an amorphous HfO₂ matrix, yielding randomly oriented orthorhombic PbHfO₃ (space group 55-Pbam; a = 0.5856 nm, b = 1.1729 nm, c = 0.8212 nm).
  • Electrical characterization shows double hysteresis loops with maximum polarizations around 30 μC/cm² and transition fields of 350–500 kV/cm depending on thickness; coercive field is <25% of hafnia ferroelectrics.
  • Temperature-dependent permittivity and polarization show a phase transition at 185 °C, most probably to the paraelectric phase, but give no clear evidence for the intermediate phase known from bulk PbHfO₃.
  • Energy storage density reaches 16 J/cm³ at 2 MV/cm, and the thinnest film shows a dielectric tunability of 221% within 1 V; the 20 nm film retains maximum polarization up to 10⁷ cycles.

Methods

  • Metal-insulator-metal capacitors were fabricated with a 100 nm Pt bottom electrode on TiO₂/SiO₂/Si, ALD PHO films grown using a super-cycle of HfO₂ and PbOx binary oxide processes with a 3:1 PbOx:HfO₂ cycle ratio at 250 °C, then Pt top electrodes sputtered and samples annealed at 700 °C or 800 °C in oxygen.
  • Three thicknesses were grown: 20 nm, 50 nm, and 200 nm; growth kinetics showed a linear growth rate of 0.07 nm/cycle, and Rutherford backscattering confirmed stoichiometric PHO within error.
  • Structural characterization used grazing-incidence X-ray diffraction and transmission electron microscopy; electrical characterization included polarization hysteresis, current-voltage, fatigue, temperature-dependent permittivity and polarization, and energy storage density measurements.

Limitations

  • The paper states that further work is needed to optimize thermal processing to reduce porosity, to clarify the interpretation of the electric field–temperature phase diagram and whether extracted critical fields above Tc have physical meaning, and to determine whether the intermediate phase is suppressed in thin films due to strain or other effects.
  • The paper states that further work is needed to fully realize imprinted PHO films centered on 0 V, and that the TiN-electrode device showed reduced leakage but strong bias-dependent asymmetry and fatigue failure after 10⁵ cycles.
  • Evident from the text: temperature-dependent dielectric and polarization measurements were performed on only the 50 nm sample, and the 200 nm film had the highest leakage current density and lowest breakdown voltage, with porosity acting as a field concentration center.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1063/5.0035730

Cites

41 of 41 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

8 of 29 cited sources checked · 4 supported · 0 flagged · accuracy not yet measured

  • Findingcitation

    The maximum permittivity falls between the temperatures of the two transitions observed in bulk PHO around 160 °C and 210 °C.

    “The maximum of permittivity falls in between the temperatures of the two transitions observed in bulk PHO around 160 ○ C and 210 ○ C. 35,36”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [35] 1970, Phys. Rev. B source
    • cites [36] 2014, J. Korean Phys. Soc. source

      The Introduction (p. 3) places PbHfO3’s two phase transitions at approximately 160 °C and 210 °C. The paper examines elastic properties, however, and the passages on the transitions (Results and Discussion, p. 5) do not establish that the permittivity reaches its maximum between them; searches for a permittivity or dielectric maximum found no such passage. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Premisecitation

    PZO films of similar thicknesses grown epitaxially with PLD show polarization values ~45 μC/cm2 compared to PHO showing ~30 μC/cm2.

    “PZO films of similar thicknesses grown epitaxially with pulsed-laser deposition show polarization values ∼45 μC/cm 240 compared to PHO showing ∼30 μC/cm 2”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [40] 2017, Chem. Mater. source

      The Results and Discussion report a saturated polarization of approximately 50 μC/cm² for PbZrO₃ films, reasonably close to the cited ~45 μC/cm². The Introduction describes laser-based growth conditions for these films. Our copy does not report a PHO polarization value or establish the claimed thickness comparison. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Findingcitation

    For all PHO samples, the coercive field is less than 25% of hafnia ferroelectrics.

    “For all of the samples, the coercive field is <25% of hafnia ferroelectrics.28”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [28] 2019, Rep. Prog. Phys. source

      The Memory applications section (page unavailable) says antiferroelectric memory can operate at a lower field than fluorite-structure ferroelectrics and reports a coercive field of about 0.7 MV/cm for antiferroelectric ZrO₂, versus 1.0–2.0 MV/cm for fluorite-structure ferroelectrics. It does not establish a coercive field below 25% of the hafnia-ferroelectric value for all PHO samples. (LLM, conf=0.78)

      Experimental — accuracy not yet measured
  • Findingnone given

    The maximum polarization and field width of the AFE→FE hysteresis widened with the addition of a TiN electrode.

    “In addition to potential imprint, the maximum polarization and field width of the AFE → FE hysteresis widened with the addition of a TiN electrode.”
    Quote in the paperSubstantial claim
  • Findingown data

    The dielectric data give no clear evidence for the intermediate phase known from bulk PbHfO3.

    “Also remarkable is the fact that the dielectric data do not show any clear evidence for the intermediate phase known in bulk PHO.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 18
  • May combine two claims. 26
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Domain mobility is known to contribute to scaling effects on the coercive fields of ferroelectrics, where Ec ∝ d^-2/3, but this scaling becomes less accurate once grains are small enough to only contain a single domain, around 100 nm.

    “Finally, domain mobility is known to contribute to scaling effects on the coercive fields of ferroelectrics, where Ec ∝ d -2/3 , 26 but this scaling becomes less accurate once grains are small enough to only contain a single domain, around 100 nm.27”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [26] 2004, Ferroelectrics source
    • cites [27] 1996, Phys. Rev. B source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The state of the art for hafnia-based AFE-like materials is closer to 60 J/cm3 and 80% efficiency at electric fields of 4500 kV/cm.

    “The state of the art for hafnia-based AFE-like materials is closer to 60 J/cm 3 and 80% efficiency at electric fields of 4500 kV/cm.28”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [28] 2019, Rep. Prog. Phys. source

      Table 1 (listed under §5, Conclusion; page unavailable) reports a hafnia-based film with 61.2 J/cm³ at 4500 kV/cm, but its efficiency is 65%, not 80%. A different hafnia-based film reaches 82% efficiency at 4500 kV/cm, but its energy-storage density is 53 J/cm³. The cited paper does not report the claimed combination in one material. (LLM, conf=0.93)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationown data

    The extracted critical fields Ef and Ea do not drop to zero at Tc, but instead reach a plateau above 200 °C, suggesting these extracted fields above Tc might not have a physical meaning.

    “However, they [Fig.3(d)] do not drop to zero at Tc, as it could have been expected from past examples of E-T phase diagrams 33 or phenomenological theory.34 Instead, both values of E f and Ea seem to reach a plateau above 200 ○ C, suggesting that these extracted fields above Tc might not have a physical meaning.”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [33] 2018, Chem. Sci. source
    • cites [34] 2016, Phys. Rev. B source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Stress is a factor affecting the phase transition field.

    “Stress is a factor affecting the phase transition field.23”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [23] 2014, Appl. Phys. Lett. source

  • May combine two claims.

    Findingown data

    The leakage current reduced for the TiN device but gained a strong bias-dependent asymmetry, while the fatigue suffered, failing after 10^5 cycles.

    “The leakage current reduced for the TiN device but gained a strong bias-dependent asymmetry, while the fatigue suffered, failing after 10 5 cycles.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    ESD increases dramatically at the AFE-FE transition field, reaching ~8 J/cm3 at 450 kV/cm and doubling at dielectric breakdown at 2000 kV/cm.

    “ESD increases dramatically at the AFE-FE transition field, reaching ∼8 J/cm 3 at 450 kV/cm and doubling at dielectric breakdown at 2000 kV/cm.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    STEM-HAADF images show small spherical pores in the interior of the PHO film, particularly along grain boundaries, and larger hemispherical pores along the film surface adjacent to the top Pt electrode.

    “Scanning TEM-high angular annular dark field (STEM-HAADF) images, which provide mass-thickness contrast, show small, spherical pores in the interior of the film, particularly along grain boundaries, with larger, hemispherical pores along the surface of the film adjacent to the interface with the top Pt electrode (Fig. S1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    With increasing thickness, thinner Bragg peaks and a general increase in intensity are observed, attributed to a combination of size effect, improvement in crystallinity, and increase in volume.

    “With increasing thickness, we observe the emergence of thinner Bragg peaks and a general increase in intensity that we attribute to a combination of size effect, improvement in crystallinity, and increase in volume.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Findingown data

    Figure 2(a) shows dielectric hysteresis loops at 1 kHz for the 20 nm, 50 nm, and 200 nm films.

    “Figure 2(a) shows the dielectric hysteresis loops at 1 kHz for the 20 nm, 50 nm, and 200 nm films obtained using the Radiant Precision Premier II testing system.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The PHO films show characteristic double hysteresis loops with maximum polarizations around 30 μC/cm2 and transition fields of 350-500 kV/cm depending on thickness.

    “Electrical characterization reveals characteristic double hysteresis loops with maximum polarizations of around 30 μC/cm 2 and transition fields of 350 kV/cm-500 kV/cm depending on the thickness.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Annealed ALD PbHfO3 films are randomly oriented orthorhombic PbHfO3 with no significant differences in preferred orientation among film thicknesses.

    “upon annealing to form a randomly oriented, orthorhombic PbHfO 3 thin film.”
    • Also stated in: § III. MATERIAL CHARACTERIZATION · plain
      “The annealed film diffractograms [Fig.1(b)] show a randomly oriented PHO film (PDF card: 04-012-0549) with no significant differences in preferred orientation among the film thicknesses.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The dielectric constant of the 50 nm PHO sample increases steadily with temperature, reaches a peak around 185 °C, and then decreases, matching the shape expected for an AFE transition.

    “We observe a steady increase in the dielectric constant that reaches a peak around T = 185 ○ C before decreasing again, which matches the shape expected for an AFE transition.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The ~50 nm PHO film thickness ranged from 54 nm to 60 nm due to roughness in the bottom Pt electrode and the film.

    “The film thickness ranged from 54 nm to 60 nm due to roughness in both the bottom Pt electrode and the film itself.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    Figure 4(c) shows polarization hysteresis for a symmetrical 20 nm Pt/PHO/Pt capacitor and the same material with an asymmetrical electrode configuration of TiN/PHO/Pt.

    “Figure 4(c) shows the polarization hysteresis for a symmetrical 20 nm Pt/PHO/Pt capacitor and the same material with an asymmetrical electrode configuration of TiN/PHO/Pt.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The relative permittivity of the 20 nm PHO sample varies from ε=200-600 at the phase transition and then <200 in the region of ferroelectric saturation.

    “The permittivity varies from ε = 200-600 at the phase transition and then <200 in the region of ferroelectric saturation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    PbHfO3 thin films were grown by ALD from Pb(DMAMP)2 and TDMAH with H2O and O3 oxidizers at a substrate temperature of 250 °C, in thicknesses from 20 nm to 200 nm.

    “Antiferroelectric PbHfO 3 is grown from atomic layer deposition precursors lead bis(dimethylaminomethylpropanolate) and tetrakis dimethylamino hafnium with H 2 O and O 3 oxidizers in thicknesses from 20 nm to 200 nm at a substrate temperature of 250 ○ C.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    Unexpectedly, the 200 nm PHO film had the highest leakage current density and lowest breakdown voltage.

    “Unexpectedly, the 200 nm film had the highest leakage current density and lowest breakdown voltage [Fig.2(b)].”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Both Pt layers exhibit a columnar microstructure, the top electrode also exhibited intergranular pores possibly from room-temperature sputtering, whereas the bottom did not.

    “While both Pt layers exhibit a columnar microstructure, the top electrode also exhibited intergranular pores possibly from the room-temperature sputtering process, whereas the bottom did not.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    A minor loop of +/-3 V taken with a DC bias of 1 V appears nearly identical to a ferroelectric polarization but with non-polar and polar states.

    “A minor loop of +/-3 V taken with a DC bias of 1 V appears nearly identical to a ferroelectric polarization [Fig.4(d)] but with non-polar and polar states.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    The Pb precursor does not wet the surface but forms a segregated, crystalline phase.

    “This supports the observations from Strnad et al. that the Pb precursor does not wet the surface but instead forms a segregated, crystalline phase.8”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [8] J. Am. Ceram. Soc. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The storage efficiency is observed by the slimness of the hysteresis loop, or the difference Ef-Ea, which has been shown to be reducible by doping PLZT.

    “The storage efficiency is observed by the slimness of the hysteresis loop, or the difference in E f -Ea, which has been shown to be reducible by doping lead lanthanum zirconated titanate (PLZT).37”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] 2019, J. Mater. Sci.: Mater. Electron. source

  • May combine two claims. The quote only partly states this claim.

    Interpretationcitation

    The porosity observed in the 50 nm sample acts as a field concentration center, and local electric field concentrations increase leakage current and provide nucleation sites for breakdown.

    “The porosity observed in the 50 nm sample in TEM is expected in the 200 nm sample, which acts as a field concentration center.30 The local concentrations of the electric field increase leakage current and provide nucleation sites for breakdown.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [30] 2016, Ferroelectrics source
    • Rests on an assumption: The porosity observed in the 50 nm sample is present in the 200 nm sample.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The intermediate phase in bulk PHO is observed between 160 °C and 215 °C and is often referred to as AFE1, although there is very little evidence that this phase is really antiferroelectric itself.

    “This intermediate phase is observed between 160 ○ C and 215 ○ C and is often referred to as AFE 1 , although there is very little evidence that this phase is really antiferroelectric itself.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] 1953, Phys. Rev. source

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The pyroelectric and electrocaloric performance of Pb-based AFEs is excellent, so further investigation in PHO is warranted.

    “The pyroelectric and electrocaloric performance of Pb-based AFEs is excellent, 41,42 so further investigation in PHO is warranted.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [41] 2018, J. Mater. Chem. C source
    • cites [42] 2014, Europhys. Lett. source

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationcitation

    PHO could have applications in low power microwave applications.

    “PHO could have applications in low power microwave applications, where recently, simulations of hafnia ferroelectrics have shown promise taking advantage of the tunability over a small applied voltage range.38”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] 2017, Appl. Phys. Lett. source

  • May combine two claims.

    Premisecitation

    AFE-like Al:HfO2 changes to the FE phase after 10^5 cycles, while Si:(Hf,Zr)O2 maintains the AFE-like phase past 10^9 cycles.

    “AFE-like Al:HfO 2 change to the FE phase after 10 5 cycles, 31 while Si:(Hf,Zr)O 2 maintains the AFE-like phase past 10 9 cycles, 15 which is in agreement with observations of related antiferroelectrics.32”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [31] 2017, J. Appl. Phys. source
    • cites [15] 2017, Appl. Phys. Lett. source
    • cites [32] 2000, Mater. Res. Bull. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The intermediate phase in bulk PHO was recently identified as incommensurate.

    “It was recently identified as incommensurate.7”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [7] 2020, Acta Crystallogr., Sect. B: Struct. Sci., Cryst. Eng. Mater. source

  • May combine two claims.

    Interpretationcitation

    The structural and electrical analysis reveals both similarities and differences to isomorphic PZO with an added benefit of more reliable ternary ALD growth from hafnia precursors vs zirconia.

    “The structural and electrical analysis reveals both similarities and differences to the isomorphic PZO with an added benefit of more reliable ternary ALD growth from hafnia precursors vs zirconia.8”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [8] J. Am. Ceram. Soc. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The increase in Pmax associated with the TiN electrode could be associated with a de-pinning of domains at the electrode interface.

    “so the increase in Pmax associated with the TiN could be associated with a de-pinning of domains at the electrode interface.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationreasoning

    The film stress and ability to template growth from oriented electrodes or seeds may be affected by this unique growth process.

    “The film stress and the ability to template growth from oriented electrodes or seeds may be affected by this unique growth process.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    PHO differs from PZO by the presence of an intermediate phase consistently observed between the paraelectric cubic phase and the orthorhombic antiferroelectric Pbam phase.

    “Besides, PHO differs from PZO by the presence of an intermediate phase consistently observed between the paraelectric cubic phase and the orthorhombic antiferroelectric Pbam phase.5”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] 1953, Phys. Rev. source

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    The unique crystallization route for PHO from ALD precursors may be exploited to lower the crystallization temperature.

    “The unique crystallization route for PHO from ALD precursors may be exploited to lower the crystallization temperature.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In bulk, PHO prepared by rolling and conventional sintering was clearly AFE, with an energy storage density of 7.6 J/cm3.

    “In the bulk, PHO prepared by rolling and conventional sintering was clearly AFE, with an energy storage density of 7.6 J/cm 3 for a bulk material.11”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [11] 2019, J. Eur. Ceram. Soc. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationnone given

    PHO is a classic antiferroelectric identified over 60 years ago, which could realize new physics and applications as a thin film.

    “PHO is a classic antiferroelectric identified over 60 years ago, which could realize new physics and applications as a thin film.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    The XRD study suggests there are no large residual stress differences among the film thicknesses, but thermal stress due to thermal expansion mismatch between film and substrate is thickness-dependent.

    “The XRD study in Figs.1(a) and 1(b) suggests that there are no large residual stress differences among the thicknesses but thermal stress due to the thermal expansion mismatch between the film and substrate are thickness-dependent.24”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [24] 2006, J. Am. Ceram. Soc. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Having higher energy storage densities at lower fields could be a benefit since voltage will increase as film thickness increases.

    “Having higher energy storage densities at lower fields could be a benefit since the voltage will increase as the film thickness increases.”
    Quote in the paperNot a substantial claim
36 of 36

  • The paper relies on this without support.

    The characteristic properties of Pb-based ferroelectrics (high polarization, low coercive field, high permittivity) are not available within the hafnium oxide material system.

    “However, the characteristic properties of Pb-based ferroelectrics such as high polarization, low coercive field, and high permittivity are not available within the hafnium oxide material system.”

  • The paper relies on this without support.

    This work is motivated by the generally superior fatigue performance of AFEs vs FEs.

    “This work is motivated by the generally superior fatigue performance of AFEs vs FEs.”

  • The authors state this as an assumption.

    The TiN electrode generated an oxygen-depleted TiOxNy interface that would increase Ef but not clearly increase polarization.

    “An assumption that the TiN generated an oxygen-depleted TiOxNy interface would increase E f but not clearly increase polarization.”

  • The paper relies on this without support.

    The AFE phase of PHO is the thermodynamically stable zero-field state.

    “Compared to AFE-like hafnia materials, the AFE phase of PHO is the thermodynamically stable zero field state that may provide long-term stability advantages.”

  • The paper relies on this without support.

    The porosity observed in the 50 nm sample is present in the 200 nm sample.

    “The porosity observed in the 50 nm sample in TEM is expected in the 200 nm sample, which acts as a field concentration center.30”

  • The paper relies on this without support.

    The polarization measurement is self-centering, so vertical shifts of unsaturated loops can appear as imprint.

    “It is challenging to de-convolute asymmetrical changes in polarization and coercive fields within the polarization hysteresis because the measurement is self-centering, and therefore, vertical shifts of unsaturated loops can appear as imprint.”
6 of 6

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Reported tunability exceeds the maximum allowed by its stated formula

    Minor

    The stated formula cannot yield 221% when both permittivities are positive: its value must be less than 100%. The paper reports positive permittivity values for these films.

1 of 1

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Authors
Hanrahan, B., Milesi-Brault, C., Leff, A., Payne, A., Liu, S., Guennou, M., & Strnad, N.
Affiliations
North Carolina State University (US)
Corresponding author
Hanrahan, Brendan
ORCID
Venue
APL Materials
Publisher
AIP Publishing
Published
2021-02-01
Volume
9
Issue
2
ISSN
2166-532X (ISSN-L)
DOI
10.1063/5.0035730
OpenAlex
W3126220445
Cited by
19
References
41
Citations by year
2026: 3 · 2025: 2 · 2024: 5 · 2023: 3 · 2022: 2 · 2021: 4
FWCI
1.01
Type
journal article
Language
en
Open access
Licence
Locations
  • APL Materials (publishedVersion, cc-by)
  • Open Repository and Bibliography (University of Luxembourg) (submittedVersion, other-oa)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • Fonds National de la Recherche Luxembourg (C16/MS/11348912/Guennou, BIAFET C16/MS/11348912/Guennou)
  • Army Research Laboratory
Topics
  • Physical Sciences › Materials Science › Materials Chemistry › Ferroelectric and Piezoelectric Materials
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Ferroelectric and Negative Capacitance Devices
  • Physical Sciences › Materials Science › Electronic, Optical and Magnetic Materials › Multiferroics and related materials
Keywords
PbHfO3, antiferroelectric thin films, atomic layer deposition precursors, orthorhombic phase, double hysteresis loop, ferroelectric-paraelectric transition, temperature dependence of permittivity, energy storage density, dielectric tunability, film thickness dependence

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