An All‐Inorganic, Transparent, Flexible, and Nonvolatile Resistive Memory

Recently, consumer electronics have moved toward data-centric applications due to the development of smart electronic devices. Moreover, electronic devices have become highly portable, wearable, and lightweight. These devices require flexible data storage with high density. Furthermore, with the growing demand for larger memory capacity, faster processing speed, and complex data computation, neuromorphic devices have emerged as the nextgeneration memory technologies. To meet the needs of next-generation memory devices, memory devices based on emerging materials such as 2D, electrochemical, and perovskite materials are suggested. Herein, the recent progress in emerging materials-based memory devices for flexible and neuromorphic device applications is reviewed. First, the functions and mechanisms of emerging material-based memory devices are described. Second, applications for emerging material-based memory devices are reviewed. Finally, the challenges and prospects for the emerging material-based memory devices are discussed.

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Section: Neuromorphic Applicationsmentioning

confidence: 99%

mentioning

confidence: 99%

Memory Devices for Flexible and Neuromorphic Device Applications

Kim

Lee

2021

Advanced Intelligent Systems

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“…The era of Internet-of-Things and machine learning has brought considerable information and, consequently, high demand for information storage electronics with nanometer-scale size and low operating power. [1][2][3] Currently, the development of traditional memory cannot follow Moore's law; therefore, that used (CH 3 NH 3 ) 3 Sb 2 Br 9 as an insulator, exploiting the selfformation of the metal Sb filament, to obtain an on/off ratio of ≈100 and a retention of 10 4 s. [14] Of 2D materials and of precursors of bismuth-related perovskite, BiI 3 , which has a high absorption coefficient in the visible region and which is composed of heavy atoms, has been considered a promising material in the field of photovoltaics, photodetection, and gamma-ray sensing. [32][33][34][35][36][37][38][39] Each layer of the BiI 3 structure consists of the I-Bi-I ionic bonding, and the interlayer is stacked by van der Waals forces.…”

Section: Introductionmentioning

confidence: 99%

“…The era of Internet‐of‐Things and machine learning has brought considerable information and, consequently, high demand for information storage electronics with nanometer‐scale size and low operating power. [ 1–3 ] Currently, the development of traditional memory cannot follow Moore's law; therefore, next‐generation memory devices such as ferroelectric random‐access memory, magnetoresistive random‐access memory, and resistive random‐access memory (RRAM) have been intensively researched and developed. [ 4–12 ] Of these innovative nonvolatile memories, RRAM offers low power consumption, fast response speed, long retention time, high scalability, multistate data‐storage capability, and a simple metal‐insulator‐metal structure.…”

Section: Introductionmentioning

confidence: 99%

Forming‐Free, Nonvolatile, and Flexible Resistive Random‐Access Memory Using Bismuth Iodide/van der Waals Materials Heterostructures

Kuo

et al. 2020

Adv Materials Inter

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next-generation memory devices such as ferroelectric random-access memory, magnetoresistive random-access memory, and resistive random-access memory (RRAM) have been intensively researched and developed. [4-12] Of these innovative nonvolatile memories, RRAM offers low power consumption, fast response speed, long retention time, high scalability, multistate data-storage capability, and a simple metalinsulator-metal structure. [9,13,14] Information storage in the RRAM is achieved by altering the resistance of its insulator. The adjustable resistance of the insulator is achieved by forming metallic or defect filaments with low resistance either by electrochemical metal dissolution or by changing the valence charge of the insulator. [15,16] Generally, the insulator used is either a transition metal oxide or perovskite oxide such as Sr 2 TiO 4 and Cr-doped SrZrO 3. [16,17] However, the synthesis of these materials often requires high temperatures and highly complex fabrication processes that are incompatible with flexible applications. [18,19] Furthermore, a high voltage is required to induce a soft breakdown of the oxide layer, which is detrimental to low-power operation. Lead-based perovskite has recently demonstrated great potential for the fabrication of RRAMs, because of its compact morphology, lowtemperature solution processability, and ionic-transport property. It functions analogously to the human synapse and offers flexible applications with a high on/off ratio, multistate-storage capability, and low set/reset voltage. [13-15,20-27] For example, Choi et al. fabricated an organo-lead halide perovskite RRAM with an on/off ratio of 10 6 , low set/reset voltage of 0.13 V, and four states of information storage. [25] Owing to the high absorption coefficient of perovskite, Zhou demonstrated optoelectronic devices with versatile functions such as photo-sensing, processing, and bit storage with the help of light pulses. [28] However, the structural stability of the perovskite in the air and the issue of its toxicity have led to uncertainty regarding its suitability as a commercial product. [29,30] To solve the issue of toxicity, Park et al. fabricated a zero-dimensional bismuth-based perovskite that had the crystal formula of A 3 Bi 2 I 9 and demonstrated a forming-free device by lowering the defect formation barrier with substitution of sodium into the Bi 3+ cation site. [31] Yang et al. reported forming-free resistive-switching devices Resistive switching devices based on halide perovskites exhibit promising potential in flexible resistive random-access memory (RRAM) owing to low fabrication cost and low processing temperature. However, the toxicity of these materials hinders their commercialization. Herein, bismuth iodide (BiI 3) is employed as an insulator in RRAM. A monolayer of graphene or hexagonal boron nitride (h-BN) is employed as a buffer layer to achieve van der Waals epitaxy of BiI 3 and meanwhile to prevent the intrusion of copper atoms. Thus, the film quality of the BiI 3 layer is greatly improved. Res...

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“…The EPW is driven by UV light while simultaneously transmitting the visible spectrum, and in this way offers onsite energy generation to power micro‐scale devices, for example, the internet of things . To be environmentally effective, the system should be made from sustainable materials such as metal‐oxide and organic photovoltaics …”

Section: Introductionmentioning

confidence: 99%

All‐Transparent Oxide Photovoltaics: AZO Embedded ZnO/NiO/AgNW Band Selective High‐Speed Electric Power Window

Ban

Patel

Nguyen

et al. 2019

Adv Elect Materials

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generate energy from the invisible radiation of the sun, while protecting us from harmful UV radiation and pollution, by employing the essential elements of a net-zero emission energy system. [3,4] The EPW is driven by UV light while simultaneously transmitting the visible spectrum, and in this way offers onsite energy generation to power micro-scale devices, for example, the internet of things. [3][4][5][6] To be environmentally effective, the system should be made from sustainable materials such as metal-oxide and organic photovoltaics. [3,[7][8][9][10][11][12] Among metal-oxides, ZnO is nontoxic, earth-abundant, and offers a bandgap of 3.2 eV, easy doping, and exciting optoelectronic processes. Tetrahedral coordination in this material results in a non-central symmetric structure and piezoelectric and pyroelectric characteristics, [13][14][15][16][17][18][19][20][21] which can be exploited by energy harvesters, for examples nano-generators [22] and other energy harvesting systems. [23][24][25] The high visible light transmittance of ZnO also makes it a potential candidate for transparent photovoltaics. [26] There have been efforts to develop ZnO based transparent photovoltaics, however, current ZnO devices typically suffer from either low photocurrent or low photovoltage. [9,[27][28][29] Despite the novelty of this class of photovoltaics, the size of the device restricts its application in an electric power window, which requires a large area. Recently, we reported a ZnO based heterostructure with various optical features, for example, room temperature excitons, demonstrated in a broadband photovoltaic [30] and pyro-phototronics [31] photodetector, which has encouraged us to develop a ZnO/NiO based highly transparent versatile 1-in. square device with enhanced performance.Here, we report a back surface field embedded all-transparent ZnO/NiO oxide heterostructure for a multi-functional EPW. First, we studied the design aspects of the AZO/ZnO/NiO device using a 1D simulation. This design revealed the vital role of the AZO layer in improving the photovoltaic performance of the ZnO/NiO via the back surface field. Following this, we studied the electrical properties of wafer-scale AZO films grown by sputtering process, and discussed the tuning of mobility and donor density (N D ). We inserted a thin layer of AZO at the interface of the ZnO/FTO and studied its photovoltaic performance Electric power windows using an all-transparent oxide photoelectric device have the potential to shield and exploit ultraviolet radiation. Herein, an Al:ZnO embedded large area all-transparent ZnO/NiO electric power window is presented. A large-scale (1-in. square) device fabricated with the structure of FTO/AZO/ZnO/NiO/AgNW exhibits a visible light transmittance >70% and photovoltaic performance with an enhanced power conversion efficiency of 3.13% under UV illumination (λ = 365 nm). The spectral attributes of this heterostructure are analyzed using I-V plots, photoresponse, and photo-carrier lifetime (τ), which reveal the co-occurren...

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An All‐Inorganic, Transparent, Flexible, and Nonvolatile Resistive Memory

Cited by 27 publications

References 60 publications

Memory Devices for Flexible and Neuromorphic Device Applications

Memory Devices for Flexible and Neuromorphic Device Applications

Forming‐Free, Nonvolatile, and Flexible Resistive Random‐Access Memory Using Bismuth Iodide/van der Waals Materials Heterostructures

All‐Transparent Oxide Photovoltaics: AZO Embedded ZnO/NiO/AgNW Band Selective High‐Speed Electric Power Window

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