Nonlinear electrical dipolar switching at single molecular scale

Choi, Jaewu; Khara, Galvin S; Song, Youngsik; Zhao, Yang

doi:10.1016/j.cplett.2005.05.109

Cited by 5 publications

(5 citation statements)

References 9 publications

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“…17 Some researchers reported the TER effect in VDF/ TrFE copolymer and VDF oligomer films with 2-6 monolayer thickness using Langmuir-Blodgett (LB) techniques. [18][19][20] However, the on/off ratios of these studies were smaller than those of inorganic systems. In our previous study, we succeeded in producing approximately 10-nmthick VDF/TrFE copolymer thin films showing clear ferroelectric hysteresis loops by choosing an appropriate fabrication process.…”

mentioning

confidence: 78%

Polarization induced resistance switching effect in ferroelectric vinylidene-fluoride/trifluoroethylene copolymer ultrathin films

Usui

Nakajima

Hashizume

et al. 2014

Applied Physics Letters

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confidence: 78%

Polarization induced resistance switching effect in ferroelectric vinylidene-fluoride/trifluoroethylene copolymer ultrathin films

Usui

Nakajima

Hashizume

et al. 2014

Applied Physics Letters

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“…The thickness of the blended polymer layer in ferroelectric diodes typically varies from several tens to several hundreds of nanometers. Ferroelectricity in P(VDF‐TrFE) is, however, stable down to a film thickness of only two monolayers (≈1 nm) . P(VDF‐TrFE) could thus be used also as a barrier material in FTJs.…”

Section: Introductionmentioning

confidence: 99%

“…P(VDF‐TrFE) could thus be used also as a barrier material in FTJs. Resistive switching effects in the tunneling regime of up to 1000% have indeed been measured on P(VDF‐TrFE) (or VDF) at room temperature . In these previous experiments, transport measurements are performed on continuous thin films using scanning tunneling microscopy or lithographically defined structures.…”

Section: Introductionmentioning

confidence: 99%

Electrode Dependence of Tunneling Electroresistance and Switching Stability in Organic Ferroelectric P(VDF‐TrFE)‐Based Tunnel Junctions

Majumdar

Chen

Qin

et al. 2017

Adv Funct Materials

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Ferroelectric tunnel junctions (FTJs) are promising candidates for nonvolatile memories and memristor-based computing circuits. Thus far, most research has focused on FTJs with a perovskite oxide ferroelectric tunnel barrier. As the need for high-temperature epitaxial film growth challenges the technological application of such inorganic junctions, more easily processable organic ferroelectrics can serve as alternative if large tunneling electroresistance (TER) and good switching durability would persist. This study reports on the performance of FTJs with a spin-coated ferroelectric P(VDF-TrFE) copolymer tunnel barrier. The use of three different bottom electrodes, indium tin oxide (ITO), La 0.67 Sr 0.33 MnO 3 , (LSMO), and Nb-doped SrTiO 3 (STO) are compared and it is shown that the polarity and magnitude of the TER effect depend on their conductivity. The largest TER of up to 10 7 % at room temperature is measured on FTJs with a semiconducting Nb-doped STO electrode. This large switching effect is attributed to the formation of an extra barrier over the space charge region in the substrate. The organic FTJs exhibit good resistance retention and switching endurance up to 380 K, which is just below the ferroelectric Curie temperature of the P(VDF-TrFE) barrier.

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“…Organic ferroelectrics 82 are an interesting alternative as they can be deposited at or near room temperature. Ferroelectricity was demonstrated in ultrathin films of organics such as PVDF-TrFE (poly(vinylidene fluoride) with trifluoroethylene) over a decade ago 21,83 , but to date, experimental reports of TER with organic ferroelectric tunnel barriers remain scarce. In 2005, Qu et al 84 observed conductivity modulation associated with polarization reversal in two monolayerthick PVDF-TrFE films through scanning tunnelling microscopy experiments.…”

Section: Electrical Control Of Spin-polarizationmentioning

confidence: 99%

Ferroelectric tunnel junctions for information storage and processing

2014

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Computer memory that is non-volatile and therefore able to retain its information even when switched off enables computers that do not need to be booted up. One of the technologies for such applications is ferroelectric random access memories, where information is stored as ferroelectric polarization. To miniaturize such devices to the size of a few nanometres, ferroelectric tunnel junctions have seen considerable interest. There, the electric polarization determines the electrical resistance of these thin films, switching the current on and off. With control over other parameters such as magnetism also being possible, ferroelectric tunnel junctions represent a promising and flexible device design. F erroelectric random access memories (FeRAMs), in which information is encoded through the ferroelectric polarization, are commercially available products with fast write speed, large read/write cycle endurance and low-power consumption 1 . In these ferroelectric capacitors, a ferroelectric thin film (typically 100 nm thick) is sandwiched between two electrodes and the remnant polarization is switched by applying an electric field between the electrodes. The widespread development of these memories is however limited owing to the capacitive readout of the information (the polarization) that prevents the scalability of FeRAMs up to gigabit densities and necessitates the rewriting of information after readout (destructive readout) 2 . In ferroelectric diodes, the current across a thick ferroelectric can be modulated by the polarization at the ferroelectric/electrode interface, giving rise to a non-destructive, resistive readout of the information 3,4 . But in these devices, the large thickness of the ferroelectric layer results in very low readout currents, limiting their miniaturization. As the ferroelectric layer thickness is decreased to a few nanometres, electronic conduction is greatly enhanced as quantum-mechanical tunnelling through the ferroelectric becomes possible 5,6 . These devices in which two electrodes sandwich a ferroelectric tunnel barrier are called ferroelectric tunnel junctions (FTJs). The tunnel transmission may be strongly modulated by the ferroelectric polarization producing giant tunnel electroresistance (TER) with OFF/ON resistance ratios reaching 10 4 (refs 7,8). Moreover, the readout current densities are much larger than in ferroelectric diodes, thereby opening the path to possible applications as high-density ferroelectric memories with non-destructive readout.Here we review the fast progress of the nascent field of FTJs and give perspectives for new physical effects and future applications. We first summarize possible electron transport mechanisms that occur when voltage is applied across ultrathin films of ferroelectrics. We then focus on experimental reports that evidence a direct correlation between ferroelectric switching and resistive switching, from local probes experiments on ferroelectric surfaces to solid-state

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Nonlinear electrical dipolar switching at single molecular scale

Cited by 5 publications

References 9 publications

Polarization induced resistance switching effect in ferroelectric vinylidene-fluoride/trifluoroethylene copolymer ultrathin films

Polarization induced resistance switching effect in ferroelectric vinylidene-fluoride/trifluoroethylene copolymer ultrathin films

Electrode Dependence of Tunneling Electroresistance and Switching Stability in Organic Ferroelectric P(VDF‐TrFE)‐Based Tunnel Junctions

Ferroelectric tunnel junctions for information storage and processing

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