Stability of polarization in organic ferroelectric metal-insulator-semiconductor structures

Kalbitz, R.; Frübing, Peter; Gerhard, Reimund; Taylor, D.M.

doi:10.1063/1.3543632

Cited by 23 publications

(15 citation statements)

References 115 publications

(345 reference statements)

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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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“…However, the cause of such hysteresis is not well understood just as we discussed above. Some researchers argued that the hysteresis was due to bistable positive and negative polarization states of the P(VDF-TrFE) film, [5][6][7] while there were still some consideration that the cause of hysteresis was due to one polarization state and one depolarization state. 10 Furthermore, the whole C-V curves shift toward positive voltage direction, which should be due to the existence of space charges in Al 2 O 3 layer and/or ferroelectric films injected during the electrical application.…”

Section: Resultsmentioning

confidence: 99%

“…19 Furthermore, as for P(VDF-TrFE)/P3HT FeFETs, R. Kalbitz et al argued that the apparent instability of depletion state arose from the development of a negative interfacial charge which more than compensated the ferroelectric-induced shift, resulting in a permanent shift in threshold voltage to positive values. 6,7 All these work indicates the existence of charge injection which shifts the threshold voltage and results in the degradation of retention property in ferroelectric memories. Finally, atmosphere exposure can also influence the retention property of ferroelectric memory devices.…”

Section: -8mentioning

confidence: 99%

“…6,7 It is reasonable that these trapped minority carriers at ferroelectric/semiconductor interface compensate, at least partly, polarization charges in ferroelectric layer and thus effectively decrease the depolarization field resulting in stable depletion state.…”

Section: -8mentioning

confidence: 99%

“…5 In P(VDF-TrFE)/P3HT FeFETs, R. Kalbitz et al observed the bi-stable polarization states even after poling process and found that the trapping of negative charges at semiconductor/ferroelectric interface resulted in the shift of flatband voltage and thus the degradation of retention. 6,7 Furthermore, B. Kam et al reported so-called triple logic states based on positive and negative polarization and also depolarization states of ferroelectric layer in P(VDF-TrFE)/pentacene FeFETs and claimed that all three states retained for at least one year. 8 While there are still many researchers who argued that depolarization in ferroelectric polymer layer greatly degraded the retention of recorded logic states in both FeFETs and memristors and, due to lack of compensation charges, polarization state did not exist even during the application of depletion voltage or immediately depolarized once the depletion voltage was removed.…”

Section: Introductionmentioning

confidence: 99%

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Piezoresponse force microscopy study on ferroelectric polarization of ferroelectric polymer thin films with various structural configurations

Zhang

Weng

et al. 2015

AIP Advances

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Ferroelectric polymer-based memory devices have attracted much attention due to their potential in low-cost flexible memories. However, bad retention property of recorded logic states limited their applications. Though mechanisms of retention degradation in ferroelectric memories are complicated and still an open question, depolarization in ferroelectric polymer layer was regarded as the main influencing factor. Here we reported our piezoresponse force microscopy (PFM) study of retention property of polarization states on various ferroelectric polymer based structures. PFM results indicated that, as for ferroelectric/semiconductor structure and ferroelectric/insulator/semiconductor structure with thin insulating layer, both positive and negative polarization states could retain for a relatively long time. Mechanisms of good retention of polarization states were discussed. The discrepancy in bad retention of logic states and good polarization retention of ferroelectric layer was also analyzed.

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Space‐Charge‐Stabilized Ferroelectric Polarization in Self‐Oriented Croconic Acid Films

Feng

Wang

et al. 2018

Adv Funct Materials

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Great progress has been made recently in molecular ferroelectrics with properties even comparable to those of inorganic ferroelectrics. However, it is difficult to develop basic thin films and devices for practical applications since most molecular ferroelectrics are uniaxial. The single polar axes of crystallites inside their films, if available, are usually oriented randomly. These can induce the components without contribution to ferroelectric polarization and a large depolarization electric field to suppress polarization. In this work, it is demonstrated that uniaxial croconic acid films in two‐terminal devices, deposited by thermal evaporation, can show effective ferroelectric polarization and nonvolatile memory switching behavior with small coercive fields of 11–30 kV cm−1. The polar c‐axes in thick crystalline films (>500 nm) are found to be self‐oriented nearly at a desired direction. With the assistance of trapped charges, stable ferroelectric polarization can be achieved, in spite of the existence of nonferroelectric components. These may pave a way to utilize uniaxial molecular ferroelectrics for various applications, such as gate dielectrics, electrets, and memory devices.

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Stability of polarization in organic ferroelectric metal-insulator-semiconductor structures

Cited by 23 publications

References 115 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

Piezoresponse force microscopy study on ferroelectric polarization of ferroelectric polymer thin films with various structural configurations

Space‐Charge‐Stabilized Ferroelectric Polarization in Self‐Oriented Croconic Acid Films

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