Understanding the switching mechanism of polymer memory

Kwan, Wei Lek; Shao, Yue; Yang, Yang

doi:10.1016/j.cap.2009.12.012

Cited by 25 publications

(14 citation statements)

References 10 publications

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“…[1,18,[27][28][29][30][31][32] However, in the present case, no single conduction mechanism can fit the characteristics of both the ON and OFF states at the same time, which indicates that different charge transport mechanisms might be involved in the bistable cycle. We found the I-V characteristics at the OFF state are well fitted to the Ohmic model and the I-V characteristics at the ON state are well fitted to the space-charge-limited current (SCLC) model.…”

Section: Resultsmentioning

confidence: 99%

Dynamic Random Access Memory Effect and Memory Device Derived from a Functional Polyimide Containing Electron Donor‐Acceptor Pairs in the Main Chain

Tian

et al. 2010

Macromol. Rapid Commun.

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A functional polyimide, hexafluoroisopropyl bis(phthalic dianhydride)/3,6-diaminocarbazole (6FDA/DAC), in which DAC serves as electron donor and 6FDA as electron acceptor, has been synthesized in our present work. Electrical characterization results on the sandwiched polyimide memory device (ITO/Thin polyimide Layer/Au) indicate that the polyimide possesses electrical bistability and the device exhibits two accessible conductivity states, which can be reversibly switched from the low-conductivity (OFF) state to the high-conductivity (ON) state with an ON/OFF current ratio of about 10(4). Different from the widely reported write-once-read-many-times (WORM) effects, the device with the 6FDA/DAC polyimide as the active layer shows dynamic random access memory (DRAM) behavior. The ON state of the device was lost immediately after removal of the applied voltage, while by applying a constant bias (e.g., 3 V) the ON state can be electrically sustained. The roles of donor and acceptor components in the polyimide main chain were elucidated through molecular simulation.

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Section: Resultsmentioning

confidence: 99%

Dynamic Random Access Memory Effect and Memory Device Derived from a Functional Polyimide Containing Electron Donor‐Acceptor Pairs in the Main Chain

Tian

et al. 2010

Macromol. Rapid Commun.

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“…Thus, if the metallic tip formed at the interface is estimated to be 10nm, the electric field it induces will be 7 × 10 5 V/cm, much smaller than the estimation from experimenters. 9 The condition for the bistable effect becomes much softer in our theory. Meanwhile, the value of U 0 for each device at OFF state is comparable to the injection barrier of electron, which is consistent with the fact that the metallic islands, as donors, matter in the whole process.…”

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Modeling the underlying mechanisms for organic memory devices: Tunneling, electron emission, and oxygen adsorbing

Yao

You

et al. 2012

Appl. Phys. Lett.

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We present a combined experimental and theoretical study to get insight into both memory and negative differential resistance (NDR) effect in organic memory devices. The theoretical model we propose is simply a one-dimensional metallic island array embedding within two electrodes. We use scattering operator method to evaluate the tunneling current among the electrode and islands to establish the basic bistable I-V curves for several devices. The theoretical results match the experiments very well, and both memory and NDR effect could be understood comprehensively. The experimental correspondence, say, the experiment of changing the pressure of oxygen, is addressed as well.PACS numbers: 73.40.Gk Memory devices based on metal-insulator-metal resistive structure with organic materials are promising in application.1 The underlying mechanism in these devices is not very clear up to now due to the complicated phenomena observed, say for example, the memory effect and the negative differential resistance (NDR) in ON state, making an obstacle for controllable improvement of the performance.2,3 Two different but correlated mechanisms have been addressed. The first one is the SimmonsVerderber (SV) model based on the space charge accumulated on some penetrated metallic islands.4 This model could be proposed to explain NDR, which is also closely related to the memory effect.2 In addition to it, electron tunneling and Coulomb blockade were also proposed, 3 indicating that the different spatial distribution of the space charge gave rise to the transition between ON and OFF state. The admittance spectroscopy provided another evidence to the SV model.5 Whereas, the basic drawback of this mechanism is that, the OFF state is always observed, in practice, during the first scanning of bias voltage, while SV model predicts the sample is initially in ON state.6 The second mechanism is the filamentary conduction, stating that there would be some penetration of metal atoms into organic layer during the deposition of top electrode, which forms some conducting filaments under relative large bias voltage, and the trap-controlled tunneling between different filaments dominates the NDR effect.7,8 The direct experimental evidence for this mechanism is from the transmission electron microscopy image, which shows the metallic filaments are formed in ON state.9 Meanwhile, the temperature insensitivity of ON state current, 10 the time dependent switch-on behavior, 11-13 and the scanning voltage and conductance dependence 14 all go together to support the filamentary mechanism. However, it is still hard to imagine the destruction and recovery of an atomic filament could respond so fast to the scanning voltage. Combining the above two mechanisms, we can get a common idea that, during the deposition of the electrode, the metallic atoms could go deeply into the organic layer and form some islands in the film, 3,15 which is crucial to the NDR effect no matter it originates from space charge or filaments.Another experiments were focusing on the ro...

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“…The resistive switching phenomenon has been observed in various materials, such as perovskite oxides SrTiO 3 [3] , solid electrolytes [4] , and polymers [5] . However, these materials have their own notable disadvantages.…”

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confidence: 99%

“…With the recent development in the microelectronic industry, a new concept, the resistive random access memory (ReRAM), has attracted considerable attention in the field of storage technology [1,2] . This memory cell based on metal/insulator/metal (MIM) structure, in which resistance can be repeatedly switched between a high and a low value by applying an electric field, is a potential replacement of flash memory in next-generation non-volatile memory (NVM).The resistive switching phenomenon has been observed in various materials, such as perovskite oxides SrTiO 3[3] , solid electrolytes [4] , and polymers [5] . However, these materials have their own notable disadvantages.…”

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confidence: 99%

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Low power consumption bipolar resistive switching characteristics of ZnO-based memory devices

Zhao¹,

Liu²,

Sun³

et al. 2012

中国光学快报

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Ag/ZnO/Pt structure resistive switching devices are fabricated by radio frequency (RF) magnetron sputtering at room temperature. The memory devices exhibit stable and reversible resistive switching behavior. The ratio of high resistance state to low resistance state can reach as high as 10 2 . The retention measurement indicates that the memory property of these devices can be maintained for a long time (over 10 4 s under 0.1-V durable stress). Moreover, the operation voltages are very low, -0. With the recent development in the microelectronic industry, a new concept, the resistive random access memory (ReRAM), has attracted considerable attention in the field of storage technology [1,2] . This memory cell based on metal/insulator/metal (MIM) structure, in which resistance can be repeatedly switched between a high and a low value by applying an electric field, is a potential replacement of flash memory in next-generation non-volatile memory (NVM).The resistive switching phenomenon has been observed in various materials, such as perovskite oxides SrTiO 3[3] , solid electrolytes [4] , and polymers [5] . However, these materials have their own notable disadvantages. For example, a solid electrolyte needs high write operation voltage, polymer is limited by low endurance, etc. Transition metal oxides (TMOs), such as ZnO, ZrO 2 , NiO, TiO 2 , and Al 2 O [6−13] 3 , are extensively studied due to their simple constituent, excellent compatibility with complementary metal oxide semiconductor (CMOS) technology, and the capability for high scalability. The current-voltage (I-V ) characteristics of the TMOs exhibit a large change resistance between high resistance state (HRS) and low resistance state (LRS) for logic off-state and logic onstate.Compared with other devices, ZnO-based devices are promising candidates for binary oxide memory application, due to their low price, long retention time, and non-destructive readout. However, several reports have shown that the operation voltages are slightly higher and devices need a forming process in the initial state [7,14] . In this letter, ZnO-based memory devices with Ag electrode were fabricated by radio frequency (RF) magnetron sputtering, and the resistive switching properties were investigated. The devices showed the bipolar resistive switching behavior with operation voltage of less than 1 V and operating current of less than 25 mA, which are significantly lower than the results of Refs. [14,15]. The non-electroforming process was obtained in our devices, which is suitable for high-density ReRAM device application. Multi-step switching processes were also observed, which can be used for multi-level memory applications.In the fabrication of the ReRAM devices with Ag/ZnO/Pt structure, approximately 100-nm ZnO film was deposited on Pt/Ti/SiO 2 /Si substrates by RF magnetron sputtering at room temperature using a metallic Zn target. The device structure is shown in Fig. 1. A thin Ti layer was inserted between the layers of Pt and SiO 2 /Si to enhance the adhesion of Pt el...

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Understanding the switching mechanism of polymer memory

Cited by 25 publications

References 10 publications

Dynamic Random Access Memory Effect and Memory Device Derived from a Functional Polyimide Containing Electron Donor‐Acceptor Pairs in the Main Chain

Dynamic Random Access Memory Effect and Memory Device Derived from a Functional Polyimide Containing Electron Donor‐Acceptor Pairs in the Main Chain

Modeling the underlying mechanisms for organic memory devices: Tunneling, electron emission, and oxygen adsorbing

Low power consumption bipolar resistive switching characteristics of ZnO-based memory devices

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