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Journal ArticleDOI

Ultra-low power, highly uniform polymer memory by inserted multilayer graphene electrode

23 Nov 2015-Vol. 2, Iss: 4, pp 044013
TL;DR: In this paper, a multilayer graphene (MLG) was inserted at the electrode/polymer interface to improve the resistive switching uniformity and reduce the power consumption.
Abstract: Filament type resistive random access memory (RRAM) based on polymer thin films is a promising device for next generation, flexible nonvolatile memory. However, the resistive switching nonuniformity and the high power consumption found in the general filament type RRAM devices present critical issues for practical memory applications. Here, we introduce a novel approach not only to reduce the power consumption but also to improve the resistive switching uniformity in RRAM devices based on poly(1,3,5-trimethyl-3,4,5-trivinyl cyclotrisiloxane) by inserting multilayer graphene (MLG) at the electrode/polymer interface. The resistive switching uniformity was thereby significantly improved, and the power consumption was markedly reduced by 250 times. Furthermore, the inserted MLG film enabled a transition of the resistive switching operation from unipolar resistive switching to bipolar resistive switching and induced self-compliance behavior. The findings of this study can pave the way toward a new area of application for graphene in electronic devices.
Citations
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Journal ArticleDOI
01 Sep 2017-Small
TL;DR: Two-dimensional nanomaterials with excellent properties including and beyond graphene, are discussed with emphasis on performance improvement by their active roles as the switching layer, insertion layer, thin electrode, patterned electrode, and edge electrode.
Abstract: Reversible chemical and structural changes induced by ionic motion and reaction in response to electrical stimuli leads to resistive switching effects in metal-insulator-metal structures. Filamentary switching based on the formation and rupture of nanoscale conductive filament has been applied in non-volatile memory and volatile selector devices with low power consumption and fast switching speeds. Before the mass production of resistive switching devices, great efforts are still required to enable stable and reliable switching performances. The conductive filament, a bridge of microscopic metal-insulator-metal structure and macroscopic resistance states, plays an irreplaceable part in resistive switching behavior, as unreliable performance often originates from unstable filament behavior. In this Review, departing from the filamentary switching mechanism and the existing issues, recent advances of the switching performance improvement through the conductive filament modulation are discussed, in the sequence of material modulation, device structure design and switching operation scheme optimization. In particular, two-dimensional (2D) nanomaterials with excellent properties including and beyond graphene, are discussed with emphasis on performance improvement by their active roles as the switching layer, insertion layer, thin electrode, patterned electrode, and edge electrode, etc.

142 citations

Journal ArticleDOI
TL;DR: Most prominent advantages offered by RRAM devices based on 2D materials include fast switching speed, less power losses, lower threshold voltage, long retention time, high electrical endurance and extended mechanical robustness.

65 citations


Cites background from "Ultra-low power, highly uniform pol..."

  • ...Graphene Graphene SWCNT PET 10(3) 10(2) 10(3) [60] Al MLG PI:PCBM PET 10(6) 10(4) 10(4) [61] Graphene Pt SiOx Si 10 2 80 10(4) [62] ITO Graphene SiOx Glass 10 5 10(2) 10(5) [77] Graphene Graphene SiOx Plastic 10 6 10(2) – [77] Graphene Al PMMA:P3BT PET 10(5) 10(7) 10(4) [64] Pt SLG Al2O3/TiO2 Si 10 2 10(3) – [67] Graphene Ti/Pt TiO2 PEN 10 2 10(2) 10(6) [65] Graphene Graphene TiOx/Al2O3/TiO2 – 10 4 10(2) 10(4) [78] MLG MLG Ta2O5–x /TaOy Glass 10 2 – – [66] Graphene Graphene ZnO Si 10(3) 50 – [79] ITO Graphene Dy2O3 Glass 10 6 10(2) 10(4) [68] Graphene LSMO BTO Si/SiO2 10 3 10(3) – [80] Al/MLG Cu pV3D3 Si/SiO2 20 10 2 – [72] BLG Al AlOx SiO2 10 3 – – [70] Sci....

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  • ...[72] also reported a highly uniform and ultra-low power polymer mem-...

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Journal ArticleDOI
TL;DR: The pV3D3-RRAM arrays fabricated via the solvent-free technique called initiated chemical vapor deposition (iCVD) process for flexible memory application showed unipolar resistive switching memory with an on/off ratio of over 10(7), stable retention time for 10(5) s, excellent cycling endurance over 10 (5) cycles, and robust immunity to mechanical stress.
Abstract: Resistive random access memory based on polymer thin films has been developed as a promising flexible nonvolatile memory for flexible electronic systems. Memory plays an important role in all modern electronic systems for data storage, processing, and communication; thus, the development of flexible memory is essential for the realization of flexible electronics. However, the existing solution-processed, polymer-based RRAMs have exhibited serious drawbacks in terms of the uniformity, electrical stability, and long-term stability of the polymer thin films. Here, we present poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane) (pV3D3)-based RRAM arrays fabricated via the solvent-free technique called initiated chemical vapor deposition (iCVD) process for flexible memory application. Because of the outstanding chemical stability of pV3D3 films, the pV3D3-RRAM arrays can be fabricated by a conventional photolithography process. The pV3D3-RRAM on flexible substrates showed unipolar resistive switching memory with an on/off ratio of over 10(7), stable retention time for 10(5) s, excellent cycling endurance over 10(5) cycles, and robust immunity to mechanical stress. In addition, pV3D3-RRAMs showed good uniformity in terms of device-to-device distribution. The pV3D3-RRAM will pave the way for development of next-generation flexible nonvolatile memory devices.

61 citations

Journal ArticleDOI
TL;DR: In this article, a novel approach to resolve the problem of random nature of the nucleation and growth of the conductive filaments (CFs) caused instability of the switching parameter, which is a major obstacle for RRAM performance improvement, was proposed by inserting graphene oxide quantum dots (GOQDs) in Zr0.5Hf0.2 (ZHO) films.
Abstract: Resistive memory (RRAM) based on a solid–electrolyte insulator is a type of critical nanoscale device with promising potential in non-volatile memory, analog circuits and neuromorphic synapse applications. However, the random nature of the nucleation and growth of the conductive filaments (CFs) causes instability of the switching parameter, which is a major obstacle for RRAM performance improvement. Herein, we report a novel approach to resolve this challenge by inserting graphene oxide quantum dots (GOQDs) in Zr0.5Hf0.5O2 (ZHO) films. The Ag/ZHO/GOQDs/ZHO/Pt stacked device exhibited a reversible bipolar resistive switching (RS) behavior under a direct current (DC) sweeping voltage. The device with GOQDs exhibited better performance than the device without GOQDs with characteristics such as reduced threshold voltage, uniform distribution of set and reset voltage, robust retention, fast switching speed and low switching power. The underlying RS mechanism of RRAM was ascribed to the formation and rupture of the nanoscale CFs inside the solid–electrolyte oxide layer. The GOQDs could guide the CF nucleation and growth direction to provide a superior uniformity of RS properties and shorten the effective distance of Ag+ motion through enhancing the local electric field on the GOQD sites. The overall device performance of the GOQDs-inserted memristor has the potential to open up a new route to improve the reliability of oxide-based RRAM, which could significantly accelerate their existing applications.

58 citations

References
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Journal ArticleDOI
TL;DR: This work shows that graphene's electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers, and allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.
Abstract: Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process The G peak slightly down-shifts This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area

13,474 citations

Journal ArticleDOI
TL;DR: A coarse-grained classification into primarily thermal, electrical or ion-migration-induced switching mechanisms into metal-insulator-metal systems, and a brief look into molecular switching systems is taken.
Abstract: Many metal–insulator–metal systems show electrically induced resistive switching effects and have therefore been proposed as the basis for future non-volatile memories. They combine the advantages of Flash and DRAM (dynamic random access memories) while avoiding their drawbacks, and they might be highly scalable. Here we propose a coarse-grained classification into primarily thermal, electrical or ion-migration-induced switching mechanisms. The ion-migration effects are coupled to redox processes which cause the change in resistance. They are subdivided into cation-migration cells, based on the electrochemical growth and dissolution of metallic filaments, and anion-migration cells, typically realized with transition metal oxides as the insulator, in which electronically conducting paths of sub-oxides are formed and removed by local redox processes. From this insight, we take a brief look into molecular switching systems. Finally, we discuss chip architecture and scaling issues.

4,547 citations

Journal ArticleDOI
24 Feb 2012-Science
TL;DR: A bipolar field-effect transistor that exploits the low density of states in graphene and its one-atomic-layer thickness is reported, which has potential for high-frequency operation and large-scale integration.
Abstract: An obstacle to the use of graphene as an alternative to silicon electronics has been the absence of an energy gap between its conduction and valence bands, which makes it difficult to achieve low power dissipation in the OFF state We report a bipolar field-effect transistor that exploits the low density of states in graphene and its one-atomic-layer thickness Our prototype devices are graphene heterostructures with atomically thin boron nitride or molybdenum disulfide acting as a vertical transport barrier They exhibit room-temperature switching ratios of ≈50 and ≈10,000, respectively Such devices have potential for high-frequency operation and large-scale integration

2,401 citations

Journal ArticleDOI
TL;DR: In this article, the authors use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on Al, Ag, Cu, Au, and Pt, while preserving its unique electronic structure, can still shift the Fermi level with respect to the conical point by 0:5 eV.
Abstract: Making devices with graphene necessarily involves making contacts with metals. We use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on Al, Ag, Cu, Au, and Pt, while preserving its unique electronic structure, can still shift the Fermi level with respect to the conical point by 0:5 eV. At equilibrium separations, the crossover from p-type to n-type doping occurs for a metal work function of 5:4 eV, a value much larger than the graphene work function of 4.5 eV. The numerical results for the Fermi level shift in graphene are described very well by a simple analytical model which characterizes the metal solely in terms of its work function, greatly extending their applicability.

2,231 citations

Journal ArticleDOI
TL;DR: This work demonstrates a TaO(x)-based asymmetric passive switching device with which it was able to localize resistance switching and satisfy all aforementioned requirements, and eliminates any need for a discrete transistor or diode in solving issues of stray leakage current paths in high-density crossbar arrays.
Abstract: Numerous candidates attempting to replace Si-based flash memory have failed for a variety of reasons over the years. Oxide-based resistance memory and the related memristor have succeeded in surpassing the specifications for a number of device requirements. However, a material or device structure that satisfies high-density, switching-speed, endurance, retention and most importantly power-consumption criteria has yet to be announced. In this work we demonstrate a TaO(x)-based asymmetric passive switching device with which we were able to localize resistance switching and satisfy all aforementioned requirements. In particular, the reduction of switching current drastically reduces power consumption and results in extreme cycling endurances of over 10(12). Along with the 10 ns switching times, this allows for possible applications to the working-memory space as well. Furthermore, by combining two such devices each with an intrinsic Schottky barrier we eliminate any need for a discrete transistor or diode in solving issues of stray leakage current paths in high-density crossbar arrays.

1,900 citations