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Journal ArticleDOI

Ultralow Current Switching in Flexible Hybrid PVP:MoS 2 /HfO x Bilayer Devices

03 Jul 2020-IEEE Transactions on Electron Devices (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 67, Iss: 8, pp 3472-3477
Abstract: We report an ultralow power consuming and forming-free hybrid flexible resistive random access memory device fabricated with poly(4-vinylphenol) (PVP):MoS2 composite and HfO x bilayer, exhibiting threshold switching with ultralow ON-current of 500 nA. While the higher concentration of MoS2 imparted the higher leakage current in the devices, the lower concentration devices exhibited decent switching with set and reset powers as low as 270 and 0.1 nW, respectively. The ultralow switching current indicates the formation of multiple weak nanosized conductive filaments created due to electromigration of Ag atoms under external bias. Moreover, heating temperature-dependent study of switching behavior confirms the metallic nature of the filament as the low resistance state (LRS) current falls significantly with rising temperature. Furthermore, these devices exhibited remarkable mechanical strength on flexible substrate with demonstration of nondestructive switching characteristics at a bending radius as low as 2.5 mm and after 100 consecutive compressive and tensile strain cycles at ±5-mm radius. The ultralow switching current with high flexibility indicates the capability of devices for advancement toward future low-power flexible memories and computing systems.
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Journal ArticleDOI
Abstract: The mechanics of film-on-foil devices is presented in the context of thin-film transistors on steel and plastic foils Provided the substrates are thin, such transistors function well after the foils are rolled to small radii of curvature When a substrate with a lower elastic modulus is used, smaller radii of curvature can be achieved Furthermore, when the transistors are placed in the neutral surface by sandwiching between a substrate and an encapsulation layer, even smaller radii of curvature can be attained Transistor failure clearly shows when externally forced and thermally induced strains add to, or subtract from, each other

665 citations


"Ultralow Current Switching in Flexi..." refers background in this paper

  • ...where d f and ds are the film and substrate thickness and Rbending is the bending radius [28]....

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Journal ArticleDOI
01 Jun 2018-
TL;DR: This Review Article examines the development of in-memory computing using resistive switching devices, where the two-terminal structure of the devices, theirresistive switching properties, and direct data processing in the memory can enable area- and energy-efficient computation.
Abstract: Modern computers are based on the von Neumann architecture in which computation and storage are physically separated: data are fetched from the memory unit, shuttled to the processing unit (where computation takes place) and then shuttled back to the memory unit to be stored. The rate at which data can be transferred between the processing unit and the memory unit represents a fundamental limitation of modern computers, known as the memory wall. In-memory computing is an approach that attempts to address this issue by designing systems that compute within the memory, thus eliminating the energy-intensive and time-consuming data movement that plagues current designs. Here we review the development of in-memory computing using resistive switching devices, where the two-terminal structure of the devices, their resistive switching properties, and direct data processing in the memory can enable area- and energy-efficient computation. We examine the different digital, analogue, and stochastic computing schemes that have been proposed, and explore the microscopic physical mechanisms involved. Finally, we discuss the challenges in-memory computing faces, including the required scaling characteristics, in delivering next-generation computing. This Review Article examines the development of in-memory computing using resistive switching devices.

593 citations


Additional excerpts

  • ...CMOS compatibility, and highly flexible structure [4]–[6]....

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Journal ArticleDOI
TL;DR: This work provides an overview of the current understanding of bipolar-switching RRAM operation, reliability and scaling, and the stability of the low- and high-resistance states will be discussed in terms of conductance fluctuations and evolution in 1D filaments containing only a few atoms.
Abstract: With the explosive growth of digital data in the era of the Internet of Things (IoT), fast and scalable memory technologies are being researched for data storage and data-driven computation. Among the emerging memories, resistive switching memory (RRAM) raises strong interest due to its high speed, high density as a result of its simple two-terminal structure, and low cost of fabrication. The scaling projection of RRAM, however, requires a detailed understanding of switching mechanisms and there are potential reliability concerns regarding small device sizes. This work provides an overview of the current understanding of bipolar-switching RRAM operation, reliability and scaling. After reviewing the phenomenological and microscopic descriptions of the switching processes, the stability of the low- and high-resistance states will be discussed in terms of conductance fluctuations and evolution in 1D filaments containing only a few atoms. The scaling potential of RRAM will finally be addressed by reviewing the recent breakthroughs in multilevel operation and 3D architecture, making RRAM a strong competitor among future high-density memory solutions.

490 citations


"Ultralow Current Switching in Flexi..." refers background in this paper

  • ...3003854 metrics mentioned above simultaneously is still on [7], [8]....

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  • ...polyvinyl alcohol; and low-dimensional materials such as graphene oxide (GO), molybdenum disulfide (MoS2), reduced GO, tungsten disulfide, and hexagonal boron nitride are the key contributors [8]–[13]....

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Journal ArticleDOI
TL;DR: This study fabricated all-inorganic perovskite films as a resistive switching layer in the Al/CsPbBr3/PEDOT:PSS/ITO/PET structure for flexible nonvolatile memory application and demonstrated the as-prepared flexible resistive random access memory devices possess reproducible and reliable memory characteristics.
Abstract: All-inorganic perovskite CsPbX3 (X = Cl, Br, or I) is widely used in a variety of photoelectric devices such as solar cells, light-emitting diodes, lasers, and photodetectors. However, studies to understand the flexible CsPbX3 electrical application are relatively scarce, mainly due to the limitations of the low-temperature fabricating process. In this study, all-inorganic perovskite CsPbBr3 films were successfully fabricated at 75 °C through a two-step method. The highly crystallized films were first employed as a resistive switching layer in the Al/CsPbBr3/PEDOT:PSS/ITO/PET structure for flexible nonvolatile memory application. The resistive switching operations and endurance performance demonstrated the as-prepared flexible resistive random access memory devices possess reproducible and reliable memory characteristics. Electrical reliability and mechanical stability of the nonvolatile device were further tested by the robust current–voltage curves under different bending angles and consecutive flexing ...

136 citations


Journal ArticleDOI
Abstract: The mechanisms of space-charge-limited (SCL) current in solids are discussed. The practical case is taken of a wide band-gap, high-resistivity material containing empty shallow trapping states but in which empty deep trapping states are eliminated by the mechanism of defect compensation described by L ongini and G reen (1956). One-dimensional and one-carrier (electron) current through a plane parallel crystal is considered for the case when one contact is ohmic and one contact is blocking. At small forward voltage, current occurs by the predominant mechanism of carrier diffusion and increases approximately as the exponential of applied voltage; in this range, current is very sensitive to temperature changes. At large forward voltage, current occurs by the predominant mechanism of carrier drift and, after a voltage threshold due to the work-function difference between anode and cathode metals, increases very nearly as the square of applied voltage; this result confirms the simplified analysis of M ott and G urney (1940) and is the solid-state analogue of the three-halves power law for space-charge-limited current in vacuum. In this range current varies as the inverse cube of crystal thickness and is relatively insensitive to temperature changes. Between these two current ranges a smooth transition occurs from a diffusion to a drift mechanism of current and a “virtual cathode” is established in the crystal; there is no evidence for the existence of a negative-resistance region during the transition as predicted by S kinner (1955). Simple and accurate analytic expressions are derived describing forward current-voltage characteristics in the exponential and square-law ranges; they show that, depending mainly on crystal thicknesses, high forward conductance or high forward resistance can be achieved. With a strongly blocking anode, reverse current is always very small and very high rectification ratios can be achieved. For current in the square-law range the Fermi-level is nearly constant through the crystal, except near the cathode and anode contacts. This justifies the distinction made by R ose (1955) between shallow traps, which lie above the Fermi-level and do not affect the form of the current-voltage characteristics, and deep traps, which lie below the Fermi-level and profoundly modify the current-voltage characteristics. The discussion is illustrated with numerical results calculated on the basis of an electron mobility of 1000 cm2/V-sec which is intermediate between the value of 200 cm2/V-sec for cadmium sulphide and 9300 cm2/V-sec for gallium arsenide. In conclusion, some possible applications are considered for space-charge-limited current in fundamental solid-state research.

133 citations


"Ultralow Current Switching in Flexi..." refers background in this paper

  • ...where εm is the dielectric constant of the material, μ is the mobility of charge carriers, θ is the ratio of free-to-total carrier density, V is the applied bias, and d is the separation between two electrodes [26]....

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