Nonvolatile Resistive Switching Memory Devices Research Articles

Unraveling Conductive Filament Formation in High Performance Halide Perovskite Memristor

AbstractHalide perovskites (HPs) are promising materials for memristor devices because of their unique characteristics. In this study, nonvolatile resistive switching memory devices based on thick MAPbI3 perovskite (800 nm) films with structure FTO/MAPbI3/polymethyl methacrylate (PMMA)/Ag are presented. Reproducible and reliable bipolar switching characteristics are demonstrated with an ultra‐low operating voltage (−0.1 V), high ON/OFF ratio (106), endurance (>2 × 103 times) and a record retention time (>105 s). The I–V curve of the first cycle exhibits self‐formed conductive filaments. These are attributed to the presence of metallic Pb resulting from an excess of PbI2 in the perovskite film. The subsequent activation process involves the formation of conductive filaments, consisting of either iodide vacancies or migrated charged metals. Numerical simulations are then carried out to understand the nature of these conductive filaments and the role of the internal electric field in the migration of iodide ions, iodide vacancies, and Ag cations. Finally, an exhaustive model is proposed that explains the set and reset processes governing the first voltage cycle and the steady state, at different voltage ranges. In summary, this work offers a novel and thorough perspective of the complete resistive switching (RS) behavior in a MAPbI3/buffer/Ag memristor, supported by numerical simulations.

Ferroelectric polarization and conductance filament coupling for large window and high-reliability resistive memory and energy-efficient synaptic devices

Ferroelectric capacitors hold great promise for non-volatile memory applications. However, the challenge lies in fabricating resistive switching devices with a high on/off ratio, excellent non-volatility, and a simple manufacturing process. Here, a novel approach is introduced by demonstrating the efficacy of the coupling effect between ferroelectric polarization and oxygen vacancy-based conductive filaments in Hf0.5Zr0.5O2 (HZO) films for the creation of non-volatile resistive switching memory devices, achieving an impressive on/off ratio of 6.8 × 103 at +1.8 V. An in-depth exploration of the resistive switching mechanism is provided and subsequently the outstanding durability and retention characteristics of these devices for resistive switching is validated. Furthermore, the device’s capacity to emulate non-volatile synaptic functionalities is assessed. Our results reveal that under pulsed conditions of 1 V/–2 V with 1 µs pulses spaced 50 ms apart, the device can robustly achieve potentiation/depression synaptic plasticity, while exhibiting energy consumption (0.16 fJ for potentiation, 0.12 fJ for depression) reduced by 1–2 orders of magnitude compared to biological synapses. This work holds significant value as a reference for the fabrication of energy-efficient, non-volatile memory and synaptic devices.

Vanadium oxide thin film deposited on Si by atomic layer deposition for non-volatile resistive switching memory devices

Vanadium dioxide (VO2) is a representative metal–insulator-transition (MIT) material that undergoes a reversible phase transition at 68 °C, which is close to room temperature. This shows the bias-triggered volatile resistance changes driven by MIT so that many studies have been made to implant VO2 as selectors for solving the sneak current problem of resistive random-access memory (ReRAM). However, the non-volatile switching of VO2 for non-volatile memory (NVM) application has not been demonstrated yet but if realized, this is truly breakthrough for low power and ultrafast NVM application. Herein, we report a successful formation of multiphase vanadium oxide on Si wafer via atomic layer deposition followed by a post-deposition annealing (PDA) process and demonstrate its applicability as a NVM device. It was confirmed that the multiphase vanadium oxide has MIT-driven abrupt resistance switching (i.e., low- and high-resistance state) at ± 1.6 V due to increased oxygen vacancies responsible for non-volatile memory property. The alternating current (AC) endurance upto 30,000 cycles and charge retention upto 3,000 sec are achieved at 2ⅹ102 of LRS/HRS current ratio. As a result, it opens the possibility of application to next-generation memory devices by reliable non-volatile MIT switching scheme.

Perforated Turbostratic Graphene As Active Layer in a Nonvolatile Resistive Switching Memory Device

Perforated turbostratic graphene (PTG) sheets have been synthesized from a natural waste material, dead bougainvillea bracts, using a single-step pyrolysis method, and a resistive switching (RS) memory device has been constructed with it for the very first time. Herein, the edges of these large-area multilayer graphene sheets are highly conducting due to the turbostratic stacking between the adjacent layers of the graphene sheets. These highly conducting PTG sheets embedded inside an insulating polymer matrix can act as an active layer for resistive switching memory devices. This hybrid structure shows nonlinear resistance change between two distinct resistance states by simple bias voltage variation. The trap-assisted space-charge-limited conduction can realize the high resistive state (HRS), whereas the low resistive state (LRS) takes place through direct conduction. To achieve the best performing device, a number of optimizations have been performed, like the variation of polymer matrices, variation of PTG and polymer concentration, active layer thickness variation, and top electrode area variation. The best performing device showed reproducibility of current–voltage data (>200 cycles), low power consumption (SET voltage <1 V), a high ON/OFF ratio (>104), a long retention time (>104 s), and a large number of endurance cycles (>103). High writing-read-erase-read speed and flexibility/bending cycle tests were also carried out on the best-performing device to examine its tenacity. The current PTG-based flexible RS memory device derived from a biowaste, dead bougainvillea bracts, can provide an important step toward developing green electronics.

Preparation and incorporation of NiSe@MoSe2 nano arrays in PVA matrix for resistive switching memory

In the present work, we have synthesized Nickel selenide@Molybdenum diselenide (NiSe@MoSe2) heteronanostructured arrays by a one-step hydrothermal method. The structural and optical analysis of nanopowder is done through Field emission scanning electron microscopy (FESEM), elemental mapping, Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), UV–vis, and Photoluminescence (PL) spectroscopy. XRD reveals the formation of a hexagonal structured system with a crystallite size of 166 nm. The bandgap of NiSe@MoSe2 nanosheets is found to be 1.71 eV, calculated from UV–vis spectra. FESEM showed the homogenous growth of NiSe@MoSe2 nanosheets while electronic transitions are investigated through PL. Further, the polymer nanocomposites of NiSe@MoSe2/PVA are synthesized by the ex-situ method at six different NiSe@MoSe2 concentrations in the PVA matrix. XRD shows good interaction between NiSe@MoSe2 and PVA polymer. The crystallinity increases as concentrations of NiSe@MoSe2 in PVA increases. FESEM shows the uniform distribution of NiSe@MoSe2 nanosheets in the PVA matrix. The two-terminal Ag/NiSe@MoSe2-PVA/FTO devices have been fabricated and characterized electrically by I-V measurements. I-V shows hysteresis behavior and also, bipolar switching is observed with a maximum Ion/Ioff ratio of ~103 at 2 wt. % NiSe@MoSe2 concentration in the PVA matrix. The good stability and reliability are checked through endurance and write-read-erase-read cyclic sequences. The obtained results open up the possibility of a next-generation non-volatile resistive switching memory device.

Laser-induced graphene-based miniaturized, flexible, non-volatile resistive switching memory devices

Laser-induced graphene-based miniaturized, flexible, non-volatile resistive switching memory devices

Nanocomposite hydroxide for resistive switching memory devices and the effect of adsorbed small molecule hexazinone

The nonvolatile resistive switching memory devices and the effect of adsorbed small molecule hexazinone have been investigated. Resistive switching behaviour of Co-Al layered double hydroxides (Co-Al LDHs)-based is gradually varied. At the same time, when Co-Al LDHs adsorbed the small molecule hexazinone, its resistive switching behaviour changed suddenly. Both memristors exhibit non-volatile data storage and good data retention characteristics. The influence of small molecule hexazinone on microcarrier transport was analyzed. This research manifests the promising potential of nanocomposite materials adsorbed electroactive small molecules in rectifying the resistive switching properties and provides some ideas for designing advanced devices of nanocomposite memristors.

Fabrication and characterization of resistive random access memory (ReRAM) devices using molybdenum trioxide (MoO3) as switching layer

The present study reports on the fabrication of non-volatile resistive switching (RS) memory device using MoO3 layers. Using a spray pyrolysis technique, different thicknesses of MoO3 thin films were deposited upon glass substrates maintaining the substrate temperature at 673 K and the physical properties were investigated. X-ray photoelectron spectroscopy (XPS) analysis elucidates that the thickness of the MoO3 thin films has a strong dependence on controlling the ratio of oxygen vacancy (VO) defects. Using MoO3 as an intermediate layer, the resistive switching characteristics of the ITO/MoO3/Ag devices were tested for 25 cycles. With an optimum thickness (~614 nm) of the MoO3 switching layer, the device exhibits a large resistive switching loop area and a higher ON/OFF ratio value of 1.28. The role of thickness-controlled oxygen vacancy (VO) defects in MoO3 towards the formation/rupture of conductive filaments in the fabricated RS memory device were explored.

Non-volatile resistive switching memory device based on ZnO-graphene oxide embedded in a polymer matrix fabricated on a flexible PET substrate

This study demonstrates non-volatile resistive switching memory using ZnO nanoparticles (NPs) embedded in GO-PVA composites deposited on pattern Al coated flexible PET substrate. The fabricated Al/ZnO-GO-PVA composite/Al/flexible PET substrate device reveals bipolar non-volatile resistive switching characteristics. This memory device shows a significant reduction in both SET voltages (VSET) and RESET voltages (VRESET) as compared to that of control Al/GO-PVA composite/Al/flexible PET substrate device. This reduction of VSET and VRESET in the case of ZnO/GO-PVA nanocomposite is due to the presence of ZnO NPs, resulting in increasing the concentration of oxygen vacancies (holes) into the GO-PVA nanocomposite. It consequently forms the conductive path between Al top electrode (TE) and Al bottom electrode (BE) which is confirmed by using X-ray photoelectron spectroscopy (XPS). This Al/ZnO-GO-PVA composite/Al/flexible PET substrate memory device is measured and tested for the flexibility, stability, retention and endurance by constantly bending the device 50 times from an angle of 180 degree (without bending) to an angle of 90 degree. Surprisingly, the resistances of both high resistance state (HRS) and low resistance state (LRS) reveal no detectable change with different bending angles (500, 700, 900, 1200, 1500) and without bending (1800). There is also no noticeable change in the current-voltage resistive switching characteristics even after the memory device is bent from 1800 to 500 angles. This memory device demonstrates good marks in mechanical endurance and flexibility, and indicates the sample is good for bendable non-volatile memory applications.

Water and air friendly alkali metals synthesis of the h-BN-C QDTs and the utilization in the non-volatile resistive switching memory devices

A novel and facile hydrothermal route was designed to produce h-BN-C quantum dots (h-BN-C QDTs) using h-BN powder as a precursor and Potassium Sodium Tartare as an intercalant. The resulting yellow solution possessed mono or few-layers of quantum dots with an average size of ~2.5 nm. Due to the incorporation of functional groups (carbon, oxygen) on the surface of h-BN, an enhancement of photo luminescent magnitude and a blue shift were observed in photoluminescence spectra from h-BN-C QDTs solution. Further, h-BN-C QDTs exhibits a bright blue fluorescence under the irradiation by a 365 nm UV light. Next, h-BN QDTs was utilized as the dielectric active layer by using simple drop casting method between the electrodes and fabricated the nonvolatile resistive switching devices. The fabricated devices exhibited the nonvolatile bipolar resistive switching characteristics with 103 ON/OFF ratio and turned ON and OFF threshold voltages of −1.9 V and +1.4 V, respectively. Further, the switching mechanisms of h-BN-C QDTs were found to be space charged trapping. It provides a route toward tailoring the optical and electrical properties of the h-BN materials and can be utilized in the future potential applications.

Nonvolatile Resistive Switching Memory Device Employing CdSe/CdS Core/Shell Quantum Dots as an Electrode Modification Layer

Accompanied with great advantages in various fields of performance, memristors show huge potential in the next generation of mainstream storage devices. However, their random distribution of resistance switching voltage has always been one of the problems in applications. In this work, a nonvolatile resistive switching memory device was proposed, which employed CdSe/CdS core/shell quantum dots (QDs) assembled as an electrode modification layer with the device configuration of Pt/CdSe–CdS QDs/TaOx/Ta. The device possesses multiple excellent resistance switching characteristics such as lower and more consistent set/reset threshold voltage and better endurance performance, which is considered as the effect of the electrode modification layer based CdSe/CdS core/shell QDs. A model with an uneven QD/Pt electrode interface was put forward to explain the different resistance switching behaviors, which may be beneficial to the development of the existing research about memristors based on metal oxides and QDs.

Bipolar Resistive Switching Characteristics and Nonvolatile Flash Memory Behavior in Polyvinylcarbazole Films

A nonvolatile resistive switching memory device based on active layers of polyvinylcarbazole (PVK) was fabricated by a spin-coating technique, and the electrical characteristics of the devices consisting of SnO2 doped with fluorine (FTO)/PVK/Ag were investigated. The experimental results revealed that the FTO/PVK/Ag device has electrical bistable nonvolatile flash memory behavior. The current remained stable for 2.3 × 103 s in both the ON state and OFF state, and the current in the ON and OFF states of the FTO/PVK/Ag device did not change substantially after 750 pulse read cycles. In addition, based on the electrochemical properties of the PVK, its resistive switching behavior was investigated. This work provides a promising solution for the development of polymer memory devices.

Non-volatile resistive switching based on zirconium dioxide: poly (4-vinylphenol) nano-composite

Recently, resistive switching devices are getting tremendous attention since they can be used for data storage in future. In this paper, we propose a non-volatile resistive switching device based on inorganic and organic nano-composite of zirconium dioxide (ZrO2) and poly (4-vinylphenol) (PVP), respectively. The nano-composite active layer ZrO2:PVP is fabricated on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrate through a spin coater technology and the top electrodes are fabricated by using silver (Ag) epoxy. The proposed device demonstrates a bipolar resistive switching at low operating voltage of ± 1.5 V with high resistance state and low resistance state of 11.438 kΩ and 262.25 Ω, respectively. To verify the non-volatility and long-term stability, the retention time is checked for more than 30 days and Roff/Ron resistance ratio is ~ 44. The proposed device is analyzed electrically and mechanically to analyze the effect of PVP in ZrO2 for better memory application and FESEM is used for the morphological characteristics of the device. These results ensure that the ZrO2:PVP nano-composite-based resistive switching device can be a possible candidate for the forthcoming flexible and low-power non-volatile resistive switching memory device.

Fabrication of carboxymethyl cellulose and graphene oxide bio-nanocomposites for flexible nonvolatile resistive switching memory devices

Nowadays the development of natural biomaterials as promising building polymers for flexible, biodegradable, biocompatible and environmentally friendly electronic devices is of great interest. As the most common natural polymers, cellulose and its derivatives have the potential to be applied in the devices owing to the easy processing, nontoxicity and biodegradability. Here, write-once-read-many-times resistive switching devices based on biodegradable carboxymethyl cellulose-graphene oxide (CMC-GO) nanocomposite are demonstrated for the first time. The hybridization sites formed by the gelation of CMC and GO molecules contribute to the excellent memory behaviors. When compared with devices base on pure GO and CMC, the device with the Al/CMC-GO/Al/SiO2 structure exhibits brilliant write-once-read-many-times (WORM) switching characteristics such as high ON/OFF current ratio of ˜105, low switching voltage of 2.22 V, excellent stability and durability. What's more, the device shows high flexibility and good resistive switching behaviors even with soft PET substrate (Al/CMC-GO/Al/PET structure). This newly designed cellulose-graphene oxide-based polymer nanocomposites are quite cheap and easy processed for large scale manufacturing of memory devices and can further contribute to future biodegradable data storage applications such as portable stretchable displays, wearable electronics and electronic skins in the coming age of artificial intelligence.

Flexible nonvolatile resistive switching memory devices based on Bi2Te3 nanosheets films

Flexible nonvolatile resistive switching memory is a promising candidate for next generation storage technologies. Exploring new materials is of crucial importance to achieve further performances of flexible nonvolatile resistive switching memory. In this work, topological insulator bismuth telluride (Bi2Te3) nanosheets films were introduced into resistive switching memory devices firstly, a typical sandwich construction of Ag/Bi2Te3/indium tin oxide/polyethylene terephthalate with good flexibility, which exhibits nonvolatile bipolar resistive switching characteristics of operation voltage, good mechanical flexibility, and good storage stability. Furthermore, trap-controlled space charge limited current, thermionic emission are the dominant conduction mechanisms in the carrier transport. This work will provide an opportunity for Bi2Te3 nanosheets to be used in flexible electronics application.

Solution-processed flexible non-volatile resistive switching device based on poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4, 8-diyl)]: polyvinylpyrrolidone composite and its conduction mechanism

Recently, solution-processed resistive switches for wearable electronics have got tremendous attention and are required for different applications due to their easy process and fabrication. Hence, this paper proposes the solution-processed resistive switching memory device based on two polymers, poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4, 8-diyl)] (F8BT) and polyvinylpyrrolidone (PVP) composite, which is fabricated on a flexible indium–tin–oxide (ITO)-coated polyethylene terephthalate (PET) substrate through spin coating technology. The fabricated device demonstrates a perfect non-volatile bipolar resistive switching through small operating voltage sweeping of ± 1.5 V, and its high-resistance state (HRS) and low-resistance state (LRS) are 92678.89 Ω and 337.85 Ω, respectively. To verify the non-volatility and long-term stability, the device is checked for more than 700 endurance cycles. During these cycles, the variations of HRS and LRS are 48 Ω and 37.35 Ω, respectively. The retention time is checked for more than 60 days, and the ROFF/RON ratio is 274.31. The bendability is carried out up to bending diameters < 10 mm, and FESEM is used for the morphological characteristics of the device. Conduction mechanism of the proposed device is supported by space charge-limited conduction (SCLC) which is explained by the log–log I–V slope-fitting curve. The results insure that the F8BT:PVP composite-based resistive switching device is to be a potential candidate for the future flexible and low-power non-volatile resistive switching memory device.

Conductance Quantization in Nonvolatile Resistive Switching Memory Based on the Polymer Composite of Zinc Oxide Nanoparticles

The composite of zinc oxide (ZnO) and polyurethane (PU) was used as an active layer. The conductance quantization was demonstrated in nonvolatile resistive switching memory devices of the indium tin oxide/PU + ZnO/Al sandwich structure. The observed bipolar resistive switching behavior is estimated to arise from the formation and dissolution of Zn filaments. Furthermore, conductance quantization with both integer and half-integer multiples of G0 (2e2/h, where e is electron charge and h is Planck’s constant) has been observed in which multilevel conductance steps are separated by half-integer multiples of G0. The observed quantized conductance phenomena in multiple well-circumscribed resistance states were appropriate for application in multilevel data memory cells.

A flexible nonvolatile resistive switching memory device based on ZnO film fabricated on a foldable PET substrate

In this work, a flexible resistive switching memory device based on ZnO film was fabricated using a foldable Polyethylene terephthalate (PET) film as substrate while Ag and Ti acts top and bottom electrode. Our as-prepared device represents an outstanding nonvolatile memory behavior with good “write–read–erase–read” stability at room temperature. Finally, a physical model of Ag conductive filament is constructed to understanding the observed memory characteristics. The work provides a new way for the preparation of flexible memory devices based on ZnO films, and especially provides an experimental basis for the exploration of high-performance and portable nonvolatile resistance random memory (RRAM).

Nonvolatile ternary resistive switching memory devices based on the polymer composites containing zinc oxide nanoparticles.

Nonvolatile ternary memory devices were fabricated from the composites polymer blends containing zinc oxide (ZnO) nanoparticles. When applying a negative bias on the top electrode, the fabricated devices with a simple sandwich structure of indium tin oxide (ITO)/composite polymer/aluminum (Al) exhibited three distinct resistance states, which could be labeled as "OFF", "ON1" and "ON2" for ternary data storage application. The ITO/polystyrene (PS) + ZnO/Al devices can endure 3 × 104 read-cycles and exhibit a retention time of 104 s. The resistance-temperature dependence at different resistance states was investigated to confirm the temperature-dependent properties. The resistance of the "OFF" and "ON1" state reveals negative temperature dependence, manifesting a typical semiconductor characteristic. The resistance of the "ON2" state exhibits positive temperature dependence, showing metallic properties.

Non-volatile resistive memory devices based on solution-processed natural DNA biomaterial

Abstract Biomaterial-based devices have demonstrated versatility in various applications and have drawn recent considerable attention. In this study, we present non-volatile resistive switching memory devices based on a natural-derived DNA biomaterial. The structure consists of a DNA-based biomaterial layer sandwiched between two electrodes, where the DNA-based biomaterial is solution-processed without sequence control or external doping of nanoparticles. The fabricated device was tested at room temperature without encapsulation and exhibited a reliable resistive switching behavior and multi-level operation with low switching voltages, 10 4 s retention time, and more than 200 cycles in memory endurance testing. Our demonstration shows that reliable memory devices can be realized using only one layer of natural DNA biomaterial, without the need for composite layers. Our characterization also provides underlying physics that may be exploited for the design and fabrication of natural DNA-based optoelectronics.