This work presents the first atomic scale evidence for ferroelectric polarization inversion on the unit cell level in a wurtzite-type material based on epitaxial Al0.75Sc0.25N thin films. The electric field induced formation of Al-polar inversion domains in the originally N-polar film is unambiguously determined by atomic resolution imaging using aberration-corrected scanning transmission electron microscopy (STEM). Anisotropic etching supports STEM results confirming a complete and homogenous polarization inversion at the film surface for the switched regions and the virtual absence of previous inversion domains in as-deposited regions. Local evidence of residual N-polar domains at the bottom electrode interface is observed and can be explained by both stress gradients and electric field deflection. The epitaxial relationship of the sapphire/AlN/Mo/AlScN multilayer stack is discussed in detail. Selected-area electron diffraction experiments and XRD pole figures reveal a Pitsch–Schrader type orientation relation between the Mo electrode and the AlScN film.
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21 January 2021
Research Article|
January 15 2021
Atomic scale confirmation of ferroelectric polarization inversion in wurtzite-type AlScN
Special Collection:
Domains and Domain Walls in Ferroic Materials
Niklas Wolff
;
Niklas Wolff
a)
1
Synthesis and Real Structure, Institute for Material Science, Kiel University
, Kaiserstr. 2, D-24143 Kiel, Germany
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Simon Fichtner
;
Simon Fichtner
2
Materials and Processes for Micro/Nanosystem Technologies, Institute for Material Science, Kiel University
, Kaiserstr. 2, D-24143 Kiel, Germany
3
Fraunhofer Institute for Silicon Technology (ISIT)
, Fraunhoferstr. 1, D-25524 Itzehoe, Germany
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Benedikt Haas
;
Benedikt Haas
4
Institute of Physics & IRIS Adlershof, Humboldt-Universität zu Berlin
, Newtonstr. 15, D-12489 Berlin, Germany
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Md Redwanul Islam
;
Md Redwanul Islam
1
Synthesis and Real Structure, Institute for Material Science, Kiel University
, Kaiserstr. 2, D-24143 Kiel, Germany
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Florian Niekiel;
Florian Niekiel
3
Fraunhofer Institute for Silicon Technology (ISIT)
, Fraunhoferstr. 1, D-25524 Itzehoe, Germany
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Maximilian Kessel
;
Maximilian Kessel
5
Fraunhofer Institute for Applied Solid State Physics, IAF
, Tullastr. 72, 79108 Freiburg, Germany
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Oliver Ambacher;
Oliver Ambacher
5
Fraunhofer Institute for Applied Solid State Physics, IAF
, Tullastr. 72, 79108 Freiburg, Germany
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Christoph Koch
;
Christoph Koch
4
Institute of Physics & IRIS Adlershof, Humboldt-Universität zu Berlin
, Newtonstr. 15, D-12489 Berlin, Germany
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Bernhard Wagner;
Bernhard Wagner
2
Materials and Processes for Micro/Nanosystem Technologies, Institute for Material Science, Kiel University
, Kaiserstr. 2, D-24143 Kiel, Germany
3
Fraunhofer Institute for Silicon Technology (ISIT)
, Fraunhoferstr. 1, D-25524 Itzehoe, Germany
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Fabian Lofink;
Fabian Lofink
3
Fraunhofer Institute for Silicon Technology (ISIT)
, Fraunhoferstr. 1, D-25524 Itzehoe, Germany
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Lorenz Kienle
Lorenz Kienle
a)
1
Synthesis and Real Structure, Institute for Material Science, Kiel University
, Kaiserstr. 2, D-24143 Kiel, Germany
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Note: This paper is part of the Special Topic on Domains and Domain Walls in Ferroic Materials.
J. Appl. Phys. 129, 034103 (2021)
Article history
Received:
October 15 2020
Accepted:
December 28 2020
Citation
Niklas Wolff, Simon Fichtner, Benedikt Haas, Md Redwanul Islam, Florian Niekiel, Maximilian Kessel, Oliver Ambacher, Christoph Koch, Bernhard Wagner, Fabian Lofink, Lorenz Kienle; Atomic scale confirmation of ferroelectric polarization inversion in wurtzite-type AlScN. J. Appl. Phys. 21 January 2021; 129 (3): 034103. https://doi.org/10.1063/5.0033205
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