Reducing Coercive-Field Scaling in Ferroelectric Thin Films via Orientation Control

Ruijuan Xu, Ran Gao, Sebastian E. Reyes-Lillo, Sahar Saremi, Yongqi Dong, Hongling Lu, Zuhuang Chen, Xiaoyan Lu, Yajun Qi, Shang Lin Hsu, Anoop R. Damodaran, Hua Zhou, Jeffrey B. Neaton, Lane W. Martin

Resultado de la investigación: Article

4 Citas (Scopus)

Resumen

The desire for low-power/voltage operation of devices is driving renewed interest in understanding scaling effects in ferroelectric thin films. As the dimensions of ferroelectrics are reduced, the properties can vary dramatically, including the robust scaling relationship between coercive field (Ec) and thickness (d), also referred to as the Janovec-Kay-Dunn (JKD) law, wherein Ec ? d-2/3. Here, we report that whereas (001)-oriented heterostructures follow JKD scaling across the thicknesses range of 20-330 nm, (111)-oriented heterostructures of the canonical tetragonal ferroelectric PbZr0.2Ti0.8O3 exhibit a deviation from JKD scaling wherein a smaller scaling exponent for the evolution of Ec is observed in films of thickness ≤ 165 nm. X-ray diffraction reveals that whereas (001)-oriented heterostructures remain tetragonal for all thicknesses, (111)-oriented heterostructures exhibit a transition from tetragonal-to-monoclinic symmetry in films of thickness ≤ 165 nm as a result of the compressive strain. First-principles calculations suggest that this symmetry change contributes to the deviation from the expected scaling, as the monoclinic phase has a lower energy barrier for switching. This structural evolution also gives rise to changes in the c/a lattice parameter ratio, wherein this ratio increases and decreases in (001)- and (111)-oriented heterostructures, respectively, as the films are made thinner. In (111)-oriented heterostructures, this reduced tetragonality drives a reduction of the remanent polarization and, therefore, a reduction of the domain-wall energy and overall energy barrier to switching, which further exacerbates the deviation from the expected scaling. Overall, this work demonstrates a route toward reducing coercive fields in ferroelectric thin films and provides a possible mechanism to understand the deviation from JKD scaling.

Idioma originalEnglish
Páginas (desde-hasta)4736-4743
Número de páginas8
PublicaciónACS Nano
Volumen12
N.º5
DOI
EstadoPublished - 22 may 2018

Huella dactilar

Ferroelectric thin films
Heterojunctions
scaling
thin films
Energy barriers
deviation
Ferroelectric materials
Remanence
Domain walls
Lattice constants
symmetry
domain wall
energy
X ray diffraction
lattice parameters
routes
Electric potential
exponents
electric potential
polarization

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Citar esto

Xu, Ruijuan ; Gao, Ran ; Reyes-Lillo, Sebastian E. ; Saremi, Sahar ; Dong, Yongqi ; Lu, Hongling ; Chen, Zuhuang ; Lu, Xiaoyan ; Qi, Yajun ; Hsu, Shang Lin ; Damodaran, Anoop R. ; Zhou, Hua ; Neaton, Jeffrey B. ; Martin, Lane W. / Reducing Coercive-Field Scaling in Ferroelectric Thin Films via Orientation Control. En: ACS Nano. 2018 ; Vol. 12, N.º 5. pp. 4736-4743.
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title = "Reducing Coercive-Field Scaling in Ferroelectric Thin Films via Orientation Control",
abstract = "The desire for low-power/voltage operation of devices is driving renewed interest in understanding scaling effects in ferroelectric thin films. As the dimensions of ferroelectrics are reduced, the properties can vary dramatically, including the robust scaling relationship between coercive field (Ec) and thickness (d), also referred to as the Janovec-Kay-Dunn (JKD) law, wherein Ec ? d-2/3. Here, we report that whereas (001)-oriented heterostructures follow JKD scaling across the thicknesses range of 20-330 nm, (111)-oriented heterostructures of the canonical tetragonal ferroelectric PbZr0.2Ti0.8O3 exhibit a deviation from JKD scaling wherein a smaller scaling exponent for the evolution of Ec is observed in films of thickness ≤ 165 nm. X-ray diffraction reveals that whereas (001)-oriented heterostructures remain tetragonal for all thicknesses, (111)-oriented heterostructures exhibit a transition from tetragonal-to-monoclinic symmetry in films of thickness ≤ 165 nm as a result of the compressive strain. First-principles calculations suggest that this symmetry change contributes to the deviation from the expected scaling, as the monoclinic phase has a lower energy barrier for switching. This structural evolution also gives rise to changes in the c/a lattice parameter ratio, wherein this ratio increases and decreases in (001)- and (111)-oriented heterostructures, respectively, as the films are made thinner. In (111)-oriented heterostructures, this reduced tetragonality drives a reduction of the remanent polarization and, therefore, a reduction of the domain-wall energy and overall energy barrier to switching, which further exacerbates the deviation from the expected scaling. Overall, this work demonstrates a route toward reducing coercive fields in ferroelectric thin films and provides a possible mechanism to understand the deviation from JKD scaling.",
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author = "Ruijuan Xu and Ran Gao and Reyes-Lillo, {Sebastian E.} and Sahar Saremi and Yongqi Dong and Hongling Lu and Zuhuang Chen and Xiaoyan Lu and Yajun Qi and Hsu, {Shang Lin} and Damodaran, {Anoop R.} and Hua Zhou and Neaton, {Jeffrey B.} and Martin, {Lane W.}",
year = "2018",
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Xu, R, Gao, R, Reyes-Lillo, SE, Saremi, S, Dong, Y, Lu, H, Chen, Z, Lu, X, Qi, Y, Hsu, SL, Damodaran, AR, Zhou, H, Neaton, JB & Martin, LW 2018, 'Reducing Coercive-Field Scaling in Ferroelectric Thin Films via Orientation Control', ACS Nano, vol. 12, n.º 5, pp. 4736-4743. https://doi.org/10.1021/acsnano.8b01399

Reducing Coercive-Field Scaling in Ferroelectric Thin Films via Orientation Control. / Xu, Ruijuan; Gao, Ran; Reyes-Lillo, Sebastian E.; Saremi, Sahar; Dong, Yongqi; Lu, Hongling; Chen, Zuhuang; Lu, Xiaoyan; Qi, Yajun; Hsu, Shang Lin; Damodaran, Anoop R.; Zhou, Hua; Neaton, Jeffrey B.; Martin, Lane W.

En: ACS Nano, Vol. 12, N.º 5, 22.05.2018, p. 4736-4743.

Resultado de la investigación: Article

TY - JOUR

T1 - Reducing Coercive-Field Scaling in Ferroelectric Thin Films via Orientation Control

AU - Xu, Ruijuan

AU - Gao, Ran

AU - Reyes-Lillo, Sebastian E.

AU - Saremi, Sahar

AU - Dong, Yongqi

AU - Lu, Hongling

AU - Chen, Zuhuang

AU - Lu, Xiaoyan

AU - Qi, Yajun

AU - Hsu, Shang Lin

AU - Damodaran, Anoop R.

AU - Zhou, Hua

AU - Neaton, Jeffrey B.

AU - Martin, Lane W.

PY - 2018/5/22

Y1 - 2018/5/22

N2 - The desire for low-power/voltage operation of devices is driving renewed interest in understanding scaling effects in ferroelectric thin films. As the dimensions of ferroelectrics are reduced, the properties can vary dramatically, including the robust scaling relationship between coercive field (Ec) and thickness (d), also referred to as the Janovec-Kay-Dunn (JKD) law, wherein Ec ? d-2/3. Here, we report that whereas (001)-oriented heterostructures follow JKD scaling across the thicknesses range of 20-330 nm, (111)-oriented heterostructures of the canonical tetragonal ferroelectric PbZr0.2Ti0.8O3 exhibit a deviation from JKD scaling wherein a smaller scaling exponent for the evolution of Ec is observed in films of thickness ≤ 165 nm. X-ray diffraction reveals that whereas (001)-oriented heterostructures remain tetragonal for all thicknesses, (111)-oriented heterostructures exhibit a transition from tetragonal-to-monoclinic symmetry in films of thickness ≤ 165 nm as a result of the compressive strain. First-principles calculations suggest that this symmetry change contributes to the deviation from the expected scaling, as the monoclinic phase has a lower energy barrier for switching. This structural evolution also gives rise to changes in the c/a lattice parameter ratio, wherein this ratio increases and decreases in (001)- and (111)-oriented heterostructures, respectively, as the films are made thinner. In (111)-oriented heterostructures, this reduced tetragonality drives a reduction of the remanent polarization and, therefore, a reduction of the domain-wall energy and overall energy barrier to switching, which further exacerbates the deviation from the expected scaling. Overall, this work demonstrates a route toward reducing coercive fields in ferroelectric thin films and provides a possible mechanism to understand the deviation from JKD scaling.

AB - The desire for low-power/voltage operation of devices is driving renewed interest in understanding scaling effects in ferroelectric thin films. As the dimensions of ferroelectrics are reduced, the properties can vary dramatically, including the robust scaling relationship between coercive field (Ec) and thickness (d), also referred to as the Janovec-Kay-Dunn (JKD) law, wherein Ec ? d-2/3. Here, we report that whereas (001)-oriented heterostructures follow JKD scaling across the thicknesses range of 20-330 nm, (111)-oriented heterostructures of the canonical tetragonal ferroelectric PbZr0.2Ti0.8O3 exhibit a deviation from JKD scaling wherein a smaller scaling exponent for the evolution of Ec is observed in films of thickness ≤ 165 nm. X-ray diffraction reveals that whereas (001)-oriented heterostructures remain tetragonal for all thicknesses, (111)-oriented heterostructures exhibit a transition from tetragonal-to-monoclinic symmetry in films of thickness ≤ 165 nm as a result of the compressive strain. First-principles calculations suggest that this symmetry change contributes to the deviation from the expected scaling, as the monoclinic phase has a lower energy barrier for switching. This structural evolution also gives rise to changes in the c/a lattice parameter ratio, wherein this ratio increases and decreases in (001)- and (111)-oriented heterostructures, respectively, as the films are made thinner. In (111)-oriented heterostructures, this reduced tetragonality drives a reduction of the remanent polarization and, therefore, a reduction of the domain-wall energy and overall energy barrier to switching, which further exacerbates the deviation from the expected scaling. Overall, this work demonstrates a route toward reducing coercive fields in ferroelectric thin films and provides a possible mechanism to understand the deviation from JKD scaling.

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KW - size effects

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KW - X-ray diffraction

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DO - 10.1021/acsnano.8b01399

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