Multi-bit organic ferroelectric memory

Khikhlovskyi, V.; Gorbunov, Andrey V.; Breemen, Albert J. J. M. van; Janssen, Raj René; Kemerink, Martijn

doi:10.1016/j.orgel.2013.09.006

Cited by 27 publications

(26 citation statements)

References 25 publications

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“…To confirm the ferroelectric property in our devices with d s ¼ 0 (that is, Al/FL/AL structure) and 60 nm, the double-wave method [25][26][27][28][29][30] was utilized to measure ferroelectric hysteresis loops, which can accurately estimate remnant polarization P r and coercive voltage V c . The detailed procedures are as follows.…”

Section: Resultsmentioning

confidence: 99%

Storage of an electric field for photocurrent generation in ferroelectric-functionalized organic devices

Dalgleish

Matsushita

et al. 2014

Nat Commun

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Organic optoelectronic devices are usually driven by the electric field generated from an electrode potential difference or bias voltage. Although poled ferroelectric domains may produce oriented stray fields, few efforts have been made to utilize them for photocurrent generation in organic devices. Here we show that large net fields caused by incomplete screening during ferroelectric polarization, and which can be 'restored' by short voltage pulses, can facilitate exciton dissociation in organic semiconductors. The oriented fields, comparable with that produced by an electrode potential difference (1B10 MV m À 1 ), here are found to be responsible for the photocurrent in our devices. A prototype for an organic photodetector driven by such stray fields is demonstrated. The photoresponsivity, without any optimization, can achieve B0.1 mA W À 1 . This study provides a different operation principle for the generation of photocurrent in organic optoelectronic devices. Furthermore, the polarity-tunable photoresponse may lead to new photoresponsive memory devices.

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Section: Resultsmentioning

confidence: 99%

Storage of an electric field for photocurrent generation in ferroelectric-functionalized organic devices

Dalgleish

Matsushita

et al. 2014

Nat Commun

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“…A 3-bit memory has been reported in a single P(VDF-TrFE) capacitor using a pulse sequence leading to partially polarized states. 29 The operation has been explained with the dipole switching theory. [29][30][31] Various multibit memories have also been reported for ferroelectric field-effect transistors (Fe-RAM) by controlling the local polarization.…”

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confidence: 99%

Retention of intermediate polarization states in ferroelectric materials enabling memories for multi-bit data storage

Zhao

Katsouras

Asadi

et al. 2016

Applied Physics Letters

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A homogeneous ferroelectric single crystal exhibits only two remanent polarization states that are stable over time, whereas intermediate, or unsaturated, polarization states are thermodynamically instable. Commonly used ferroelectric materials however, are inhomogeneous polycrystalline thin films or ceramics. To investigate the stability of intermediate polarization states, formed upon incomplete, or partial, switching, we have systematically studied their retention in capacitors comprising two classic ferroelectric materials, viz. random copolymer of vinylidene fluoride with trifluoroethylene, P(VDF-TrFE), and Pb(Zr,Ti)O3. Each experiment started from a discharged and electrically depolarized ferroelectric capacitor. Voltage pulses were applied to set the given polarization states. The retention was measured as a function of time at various temperatures. The intermediate polarization states are stable over time, up to the Curie temperature. We argue that the remarkable stability originates from the coexistence of effectively independent domains, with different values of polarization and coercive field. A domain growth model is derived quantitatively describing deterministic switching between the intermediate polarization states. We show that by using well-defined voltage pulses, the polarization can be set to any arbitrary value, allowing arithmetic programming. The feasibility of arithmetic programming along with the inherent stability of intermediate polarization states makes ferroelectric materials ideal candidates for multibit data storage.

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“…However, the injection barrier can be tuned with the assistance of the stray field of the ferroelectric polarization charges. [7,9] The ascending curve in Figure 1a shows that upon increasing the applied voltage the ferroelectric becomes polarized which consequently lowers the injection barrier, leading to a significant current increase which occurs at around the coercive voltage of +10 V. [20] As the ferroelectric preserves its polarization state when the applied voltage is turned off, the descending part of the I-V curve does not follow the ascending one. Thus the positive part of the I-V sweep demonstrates significant hysteresis behaviour and the device can be programmed to the ON and OFF states.…”

Section: Introductionmentioning

confidence: 99%

“…In order to understand the underlying mechanism of the information loss the depolarization in the ferroelectric phase of the device was studied using the double-wave method (DWM). In the DWM a sequence of one 'set' and two (identical) 'probe' pulses is applied and the corresponding switching currents are measured [20] ( Figure S1 in SI). The set signal is used to set the desired polarization state of the ferroelectric.…”

Section: Introductionmentioning

confidence: 99%

Data retention in organic ferroelectric resistive switches

Khikhlovskyi

Breemen

Janssen

et al. 2016

Organic Electronics

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Solution-processed organic ferroelectric resistive switches could become the long-missing non-volatile memory elements in organic electronic devices. To this end, data retention in these devices should be characterized, understood and controlled. First, it is shown that the measurement protocol can strongly affect the 'apparent' retention time and a suitable protocol is identified. Second, it is shown by experimental and theoretical methods that partial depolarization of the ferroelectric is the major mechanism responsible for imperfect data retention. This depolarization occurs in close vicinity to the semiconductor-ferroelectric interface, is driven by energy minimization and is inherently present in this type of phase-separated polymer blends. Third, a direct relation between data retention and the charge injection barrier height of the resistive switch is demonstrated experimentally and numerically. Tuning the injection barrier height allows to improve retention by many orders of magnitude in time, albeit at the cost of a reduced on/off ratio. Corresponding Author

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Multi-bit organic ferroelectric memory

Cited by 27 publications

References 25 publications

Storage of an electric field for photocurrent generation in ferroelectric-functionalized organic devices

Storage of an electric field for photocurrent generation in ferroelectric-functionalized organic devices

Retention of intermediate polarization states in ferroelectric materials enabling memories for multi-bit data storage

Data retention in organic ferroelectric resistive switches

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