Surface chemical bonding states and ferroelectricity of Ce-doped BiFeO3 thin films prepared by sol–gel process
Bi 1− x Ce x FeO 3 ( x = 0, 0.05, 0.1, 0.15 and 0.20) (BCFO) thin films were deposited on Pt/TiN/Si 3 N 4 /Si substrates by sol–gel technique. Crystal structures, surface chemical compositions and bonding states of BCFO films were investigated by X-ray diffraction and X-ray photoelectron spectrosco...
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Veröffentlicht in: | Journal of sol-gel science and technology 2008-12, Vol.48 (3), p.261-266 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Bi
1−
x
Ce
x
FeO
3
(
x
= 0, 0.05, 0.1, 0.15 and 0.20) (BCFO) thin films were deposited on Pt/TiN/Si
3
N
4
/Si substrates by sol–gel technique. Crystal structures, surface chemical compositions and bonding states of BCFO films were investigated by X-ray diffraction and X-ray photoelectron spectroscopy (XPS), respectively. Compared to BiFeO
3
(BFO) counterparts, the fitted XPS narrow-scan spectra of Bi 4f
7/2
, Bi 4f
5/2
, Fe 2p
3/2
, Fe 2p
1/2
and O 1s peaks for Bi
0.8
Ce
0.2
FeO
3
film shift towards higher binding energy regions by amounts of 0.33, 0.29, 0.43, 0.58 and 0.49 eV, respectively. Dielectric constants and loss tangents of the BCFO (
x
= 0, 0.1 and 0.2) film capacitors are 159, 131, 116, 0.048, 0.041 and 0.035 at 1 MHz, respectively. Bi
0.8
Ce
0.2
FeO
3
film has a higher remnant polarization (
P
r
= 2.04 μC/cm
2
) than that of the BFO (
P
r
= 1.08 μC/cm
2
) at 388 kV/cm. Leakage current density of the Bi
0.8
Ce
0.2
FeO
3
capacitor is 1.47 × 10
−4
A/cm
2
at 388 kV/cm, which is about two orders of magnitude lower than that of the BFO counterpart. Furthermore, Ce cations are feasibly substituted for Bi
3+
in the Bi
0.8
Ce
0.2
FeO
3
matrix, possibly resulting in the enhanced ferroelectric properties for the decreased grain sizes and the reduced oxygen vacancies. |
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ISSN: | 0928-0707 1573-4846 |
DOI: | 10.1007/s10971-008-1825-x |