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In a short-circuited ferroelectric capacitor with a metal-ferroelectric-metal (MFM) structure, a charge distribution of screening charges forms at the metal-ferroelectric interface so as to screen the electric displacement of the ferroelectric. Due to these screening charges, there is a voltage drop
50:
needed to flip the memory cell to the opposite state is measured and the previous state of the cell is revealed. This means that the read operation destroys the memory cell state, and has to be followed by a corresponding write operation, in order to write the bit back. This makes it similar to (now
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55:. The requirement of a write cycle for each read cycle, together with the high but not infinite write cycle limit is a potential problem for some special applications.
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material. In contrast, traditional capacitors are based on dielectric materials. Ferroelectric devices are used in digital electronics as part of
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across the ferroelectric capacitor with screening in the electrode layer that can be obtained using the Thomas-Fermi approach as follows:
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Dawber; et al. (2003). "Depolarization corrections to the coercive field in thin-film ferroelectrics".
340:{\displaystyle E_{e}={\frac {\epsilon _{f}}{\epsilon _{e}}}E_{f}-{\frac {4\pi }{\epsilon _{e}}}P_{s}}
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In memory applications, the stored value of a ferroelectric capacitor is read by applying an
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241:{\displaystyle E_{f}={\frac {V+8\pi P_{s}a}{d+\epsilon _{f}\left(2a\right)}}}
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are the electric fields in the film and electrode at the interface,
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are the dielectric constants of the film and the metal electrode.
31:, or in analog electronics as tunable capacitors (varactors).
580:{\displaystyle V=E_{f}d\Rightarrow E_{f}={\frac {V}{d}}}
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124:{\displaystyle V=E_{f}d+E_{e}\left(2\lambda \right)}
407:{\displaystyle a={\frac {\lambda }{\epsilon _{e}}}}
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38:Schematic of a ferroelectric capacitor
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374:is the spontaneous polarization,
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461:{\displaystyle \epsilon _{e}}
434:{\displaystyle \epsilon _{f}}
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645:10.1088/0953-8984/15/24/106
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490:{\displaystyle \lambda =0}
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497:or for thick films, with
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677:Ferroelectric materials
153:is the film thickness,
17:Ferroelectric capacitor
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516:{\displaystyle d\gg a}
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633:J Phys Condens Matter
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367:{\displaystyle P_{s}}
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53:ferrite core memory
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601:Ferroelectric RAM
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146:{\displaystyle d}
29:ferroelectric RAM
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596:Ferroelectricity
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46:. The amount of
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613:FeRAM Tutorial
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607:External links
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44:electric field
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25:ferroelectric
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639:(24): 393.
23:based on a
672:Capacitors
666:Categories
619:References
51:obsolete)
653:250818321
552:⇒
508:≫
479:λ
450:ϵ
423:ϵ
394:ϵ
390:λ
317:ϵ
312:π
303:−
282:ϵ
272:ϵ
211:ϵ
186:π
114:λ
21:capacitor
590:See also
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441:&
414:, and
59:Theory
48:charge
649:S2CID
133:Here
19:is a
248:and
641:doi
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565:=
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536:=
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482:=
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385:=
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309:4
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266:=
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221:(
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204:d
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183:8
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171:=
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141:d
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111:2
107:(
101:e
97:E
93:+
90:d
85:f
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77:=
74:V
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