Layer control of Sr1.8Bi0.2Nan-3NbnO3n+1 (n = 3–5) perovskite nanosheets: dielectric to ferroelectric transition of film deposited by Langmuir Blodgett method
Solution-based processable high-k 2-dimensional (2D) ferroelectrics have attracted significant interest for use in next-generation nanoelectronics. Although few studies on potential 2D ferroelectric nanosheets in local areas have been conducted, reports on the thin-film characteristics applicable to...
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Veröffentlicht in: | NPJ 2D materials and applications 2023-08, Vol.7 (1), p.53-7, Article 53 |
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Sprache: | eng |
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Zusammenfassung: | Solution-based processable high-k 2-dimensional (2D) ferroelectrics have attracted significant interest for use in next-generation nanoelectronics. Although few studies on potential 2D ferroelectric nanosheets in local areas have been conducted, reports on the thin-film characteristics applicable to the device are insufficient. In this study, we successfully synthesize high-k 2D Sr
1.8
Bi
0.2
Na
n-3
Nb
n
O
3n+1
(octahedral units,
n
= 3–5) nanosheets by the engineering of the
n
of NbO
6
octahedral layers with A-site modification, and realized ferroelectric characteristics in ultrathin films (below 10 nm). The nanosheets are synthesized by a solution-based cation exchange process and deposited using the Langmuir-Blodgett (LB) method. As increasing the NbO
6
octahedral layer, the thickness of the nanosheets increased and the band gaps are tuned to 3.80 eV (
n
= 3), 3.76 eV (
n
= 4), and 3.70 eV (
n
= 5). In addition, the dielectric permittivity of the 5-layer stacked nanofilm increase to 26 (
n
= 3), 33 (
n
= 4), and 62 (
n
= 5). In particular, the increased perovskite layer exhibits large distortions due to the size mismatch of Sr/Bi/Na ions at the A-site and promotes local ferroelectric instability due to its spontaneous polarization along the c-axis caused by an odd
n
number. We investigate the stable ferroelectricity in Pt/ 5-layer Sr
1.8
Bi
0.2
Na
2
Nb
5
O
16
/ Nb:STO capacitor by polarization-electric field (P-E) hysteresis; the coercive electric field (E
c
) was 338 kV cm
−1
and the remnant polarization (P
r
) 2.36 μC cm
−2
. The ferroelectric properties of ultrathin 2D materials could drive interesting innovations in next-generation electronics. |
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ISSN: | 2397-7132 2397-7132 |
DOI: | 10.1038/s41699-023-00418-9 |