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Electrical triggering of a metal-insulator transition (MIT) often results in the formation of characteristic spatial patterns such as a metallic filament percolating through an insulating matrix or an insulating barrier splitting a conducting matrix. When MIT triggering is driven by electrothermal effects, the temperature of the filament or barrier can be substantially higher than the rest of the material. Using X-ray microdiffraction and dark-field X-ray microscopy, we show that electrothermal MIT triggering leads to the development of an inhomogeneous strain profile across the switching device, even when the material does not undergo a pronounced, discontinuous structural transition coinciding with the MIT. Diffraction measurements further reveal evidence of unique features associated with MIT triggering including lattice distortions, tilting, and twinning, which indicate structural nonuniformity of both low- and high-resistance regions inside the switching device. Such lattice deformations do not occur under equilibrium, zero-voltage conditions, highlighting the qualitative difference between states achieved through increasing temperature and applying voltage in nonlinear electrothermal materials. Electrically induced strain, lattice distortions, and twinning could have important contributions in the MIT triggering process and drive the material into nonequilibrium states, providing an unconventional pathway to explore the phase space in strongly correlated electronic systems.

In this work, we have investigated the resistive switching (RS) properties of metal-insulator-metal (MIM) RRAM (resistive random-access memory) devices based on Hafnium Oxide (HfO2) films. A systematic study on the effect of substrate temperature on the crystallinity and its correlation with RS behaviour of HfO2 films deposited on platinized silicon using the Pulsed Laser Deposition (PLD) has been performed. Grazing-incidence X-ray diffraction and X-ray reflectivity techniques were employed to analyse the phase formation and the thickness of the films, respectively. The films were deposited at two different substrate temperatures 400 °C and 700 °C. A lower substrate temperature led to an amorphous film while the higher substrate temperature resulted in a polycrystalline film. The effect of change in amorphous to polycrystalline nature of HfO2 films with substrate temperature was studied on RS behaviour of these films. To assess the RS behaviour, DC electrical characterization was conducted on stacked W/HfO2/Pt thin films. The electrical characterization revealed forming-free bipolar RS behavior in both the films along with a digital SET and gradual RESET. The resistance of the films was found to be dependent on phase and microstructure which in turn depends upon substrate temperature. This study would be useful for the optimization of RS behaviour by tuning the crystallinity of the HfO2 films through processing temperature. [ABSTRACT FROM AUTHOR]

The rapid development of brain‐inspired computing requires new artificial components and architectures for its hardware implementation. In this regard, memristive devices emerged as potential candidates for artificial synapses because of their ability to emulate the plasticity of the biological synapses. In this work, the synaptic behavior of the TiN/La2NiO4+δ/Pt memristive devices based on thermally annealed La2NiO4+δ films is thoroughly investigated. Using electron energy loss spectroscopy (EELS), it is shown that post‐deposition annealing using inert (Ar) or oxidizing (O2) atmospheres affects the interstitial oxygen content (δ) in the La2NiO4+δ films. Electrical characterization shows that both devices exhibit long‐term potentiation/depression (LTP/LTD) and spike‐timing‐dependent plasticity (STDP). At the same time, the Ar annealed TiN/La2NiO4+δ/Pt device demonstrates filamentary‐like behavior, fast switching, and low energy consumption. On the other hand, the O2 annealed TiN/La2NiO4+δ/Pt devices are forming‐free, exhibiting interfacial‐like resistive switching with slower kinetics. Finally, the simulation tools show that spiking neural network (SNN) architectures with weight updates based on the experimental data achieve high inference accuracy in the digit recognition task, which proves the potential of TiN/La2NiO4+δ/Pt devices for artificial synapse applications. [ABSTRACT FROM AUTHOR]

This study investigates the resistive switching characteristics of Ag nanoparticle (AgNP)-incorporated pectin (pectin-AgNP) as a memristive thin film, with varying concentrations of AgNP (0.0 wt.%, 0.5 wt.%, and 1.0 wt.%) and pectin (5.0 mg/L, 5.5 mg/L, 6.0 mg/L, 6.5 mg/L, and 7.0 mg/L), sandwiched between Au and indium tin oxide (ITO) electrodes on glass substrate. The structural, chemical, and electrical properties of these pectin-AgNP thin films were evaluated. With AgNP concentration of 0.5 wt.% in a pectin concentration of 5.5 mg/mL, the Fourier transform infrared (FTIR) spectra indicated the highest presence of C–O bonds. This suggests the incorporation of AgNP and the formation of more linear and extended pectin chains established by glycosidic bonds. The abundance of C–O bonds contributed significantly to the increase in the resistance of the thin film, consequently yielding the highest ON/OFF ratio (7.2 × 103) observed among the samples. The electronic and thermochemical mechanisms governing the resistive switching behaviours were also proposed. [ABSTRACT FROM AUTHOR]

With the advent of the internet era, wearable electronic devices and flexible electronic technology are rapidly emerging, and new resistive random access memory (RRAM) based on flexible substrates have thus gained extensive attention. Here, the flexible Bi 0·95 Er 0·05 FeO 3 /ZnO/La 0·66 Sr 0·34 MnO 3 (BEFO/ZnO/LSMO) heterostructure is prepared on Mica substrate using the sol-gel method. The high resistance state (HRS) to low resistance state (LRS) ratio consistently surpasses 102 under the flat and the 15 mm bending radius state. There is no significant change in the resistive switching (RS) behavior after 30 I–V curve cycles and 103 write/erase operations on the BEFO/ZnO/LSMO heterostructure, which reflects excellent stability. In addition, the device still works properly at 175 °C for dynamic conversion between HRS and LRS. The observed RS behavior in the BEFO/ZnO/LSMO heterostructure is attributed to ion migration and alterations in the potential barrier height at the interfaces. These results suggest that the BEFO/ZnO/LSMO heterostructure based on a flexible Mica substrate plays a crucial role in the development of next-generation portable and flexible electronic systems due to its excellent flexibility and thermal stability. [ABSTRACT FROM AUTHOR]

Light‐based modulation on resistive switching has opened a new route for development of the devices for advanced applications like integrated switching with memory functionality, neuromorphic computing, and humanoid robotics. This article presents the wafer‐scalable process to fabricate titanium dioxide (TiO2)/porous silicon (P‐Si)‐based heterostructures for memristor applications. The resistive switching performance of the memristor is analyzed using electrical/optical stimulation. The fabricated devices offer enhanced performance metrics during optical stimulation when compared to electrical stimulation. The memristor device offers the paired pulse facilitation (PPF) index of ≈519% (during optical stimulation), which is 3.4 times of the electrical stimulation. Further, the stability and reliability measurements are performed at different temperatures especially (room temperature to 348 K) under 450 nm illumination. The testing results prove that the developed TiO2/P‐Si‐based memristors are suitable for the next‐generation computation systems development. [ABSTRACT FROM AUTHOR]

Memristors have emerged as a promising candidate to mimic the human behavior and thus unlocking the potential for bio‐inspired computing advancement. However, these devices operate at a voltages which are still far from the energy‐efficient biological counterpart, which uses an action potential of 50–120 mV to process the information. Here, a diffusive memristor is reported from synthetic WSe2 fabricated in Ag/WSe2/Au vertical device geometry. The devices operate at bio‐voltages of 40–80 mV with Ion/Ioff ratio of 106 and steep switching turn ON and OFF slopes of 0.77 and 0.88 mV per decade, respectively. The power consumption in standby mode and power per set transition are found to be 10 fW and 64 pW, respectively. Further, the diffusive memristors are utilized to emulate the nociceptor, a special receptor for sensory neurons that selectively responds to noxious stimuli. Nociceptor in turn imparts a warning signal to the central nervous system which then triggers the motor response to take precautionary actions to prevent the body from injury. The key features of a nociceptor including “threshold”, “relaxation”, “no‐adaptation” and “sensitization” are demonstrated using artificial nociceptors. These illustrations imply the feasibility of developing low‐power diffusive memristors for bio‐inspired computing, humanoid robots, and electronic skins. [ABSTRACT FROM AUTHOR]

Copper sulfides exhibit various significant physical properties and have wide potential applications. In order to synthesize copper sulfides and investigate the anion substitution possibility of Cu3P, we immersed Cu3P in sodium sulfide solution. From X‐ray diffraction spectra results, copper sulfides, namely Cu2S and Cu7.2S4, were observed, indicating that anion substitution between S2− and P3− ions did occur. Consequently, we investigated the resistive switching (RS) properties of these two phases in the presence of Cu3P. We found that the Cu2S‐Cu3P composite exhibited a high Off/On ratio (88) and a long retention time (>103 s). However, the Cu7.2S4‐Cu3P composite exhibited no RS performance. In addition, we discussed the conduction and resistive switching mechanisms. Our work enriches the preparation method of copper sulfides and provides a reference for enhancing RS performance. [ABSTRACT FROM AUTHOR]

The coexistence and coupling of capacitive and memristive effects have been an important subject of scientific interest. While the capacitive effect in memristors has been extensively studied, the reciprocal scenario of the memristive effect in capacitors remains unexplored. In this study, we introduce a supercapacitor-memristor (CAPistor) concept, which is constructed by leveraging non-linear ion transport within the pores of a metal-organic framework zeolitic-imidazolate framework (ZIF-7). Within the nanochannels of the ZIF-7 electrode in an aqueous pseudocapacitor, the anionic species (OH−) of the electrolyte can be enriched and dissipated in different voltage regimes. This difference leads to a hysteresis effect in ion conductivity, constituting a memristive behavior in the pseudocapacitor. Thus, the pseudocapacitor-converted CAPistor seamlessly integrates the programmable resistance and memory functions of an ionic memristor into a supercapacitor, demonstrating enormous potential to extend the traditional energy storage applications of supercapacitors into emerging fields, including biomimetic nanofluidic ionics and neuromorphic computing. [ABSTRACT FROM AUTHOR]

We report on the evidenced giant vertical magnetization shift in Ag/NiO/Fe/FTO bilayers when electric field Ez (electric field applied in z direction) and magnetic field Hz (magnetic field applied in z direction) are parallel to each other. Calculated vertical magnetization shift (ME) is determined to be 1168 emu/cc (259%) for applied voltage of +1.5 V, while it is −1142 emu/cc (252%) for –1.5 V respectively. Such a huge change is attributed to the pinning of spins at the interface through resistive switching phenomena that is governed through oxygen ion migration at the interface. The quantitative correlation between interfacial anisotropy energy and the applied electric field is established. Determined coefficient pertinent to electric-field-control of magnetic anisotropy is found to be 1.19 × 10−8 erg/V cm when Ez and Hz are parallel to each other. A reversible and reproducible magnetization switching is demonstrated by applying +1.5 V and −1.5 V repeatedly, which demonstrates robustness of the magnetization switching in fabricated device. Indeed, intermediate magnetization states are availed through voltage, which may be of great interest for the multi-bit data storage and energy efficient spintronic devices. [ABSTRACT FROM AUTHOR]

We present a transparent memristor with a rough-surface (RS) bottom electrode (BE) with enhanced performance and reliability for a gasistor, which is a gas sensor plus a memristor, and its application in this paper. The transparent memristor, with an RS BE, exhibited low forming voltages (0.8 V) and a stable resistive switching behavior, with high endurance and an on/off ratio of about 125. This improvement is due to the better control of the electric field distribution and the oxygen vacancy concentration when applying the RS BE to transparent memristors. Maintaining the stability of the conducting filament in an ambient air environment for extended periods of time is crucial for the application of memristors as gasistors. The memristor with an RS BE demonstrates an ability to sustain a stable-current state for approximately 104 s. As a result, it is shown that the proposed transparent memristor with an RS BE can significantly enhance the device's reliability for gasistor applications. [ABSTRACT FROM AUTHOR]

Memristor devices for resistive-switching memory and artificial synapses have emerged as promising solutions for overcoming the technological challenges associated with the von Neumann bottleneck. Recently, due to their unique optoelectronic properties, solution processability, fast switching speeds, and low operating voltages, quantum dots (QDs) have drawn substantial research attention as candidate materials for memristors and artificial synapses. This review covers recent advancements in QD-based resistive random-access memory (RRAM) for resistive memory devices and artificial synapses. Following a brief introduction to QDs, the fundamental principles of the switching mechanism in RRAM are introduced. Then, the RRAM materials, synthesis techniques, and device performance are summarized for a relative comparison of RRAM materials. Finally, we introduce QD-based RRAM and discuss the challenges associated with its implementation in memristors and artificial synapses. [ABSTRACT FROM AUTHOR]

With the growing prevalence of neuromorphic computing algorithms, there is a growing need for electronic synaptic devices. In this study, using Li4+ x Ti5O12 (LTO) as the resistive switching layer, C as the lithium ions storage layer, and Li1+ x Al x Ti2− x (PO4)3 (LATP) as ions transmission layer, a synaptic device is designed with the structure of Pt/C/LATP/LTO/PtSi to imitate the lithium-ion battery. Variation of the thickness of the LATP layer in the LTO device is explored to show the impact on the device's synaptic performance. With a LATP thickness of 100 nm, the LTO synaptic device exhibits a high potentiation/depression cyclic stability of over 50 cycles, improved potentiation/depression linearity and smoothness. The synaptic potentiation/depression is ascribed to migration of lithium ions from the LTO layer. A conductance relaxation characteristic of the device is explained by battery self-discharge phenomenon. The battery effect in the LTO device also led to generation of electromotive force. The study of battery-imitating LTO synaptic device offers new perspectives on the connection between battery and analog synaptic device. [ABSTRACT FROM AUTHOR]

In conventional designs, sensory systems are segregated from memory and computing units. The conversion and transmission of data from analog sensing domains to digital storage result in inefficient power utilization and increased latency. Here, a multifunctional memristor capable of detecting gamma radiation while also serving as a data storage device and an artificial synapse is reported. Large‐scale integration of oxide‐based memristors for artificial neural networks faces major challenges due to the sneak‐path current issue in crossbar arrays. Consequently, material combinations and fabrication variables significantly shape nanoscale processes, which are essential in determining resistive switching properties and functionalities. Resistive switching in AlFeO3 is studied using different electrode materials (silver (Ag), gold (Au), chromium (Cr), fluorine‐doped tin oxide, and silicon), embedding metal (Ag, Au) nanocrystals to engineer a class of tunable memories capable of functioning as selector, memory, artificial synapse, and dosimeter. Techniques like electrode engineering, nanocrystal seeding, and temperature‐dependent thin film deposition are employed to tune resistive and threshold switching functionalities. Accessing different functionalities requires changing the electrode materials or changing the synthesis conditions of the AlFeO3 resistive switching layer and are not interconvertible in the same device simultaneously. The devices emulate critical neural functions and demonstrate interconversion dynamics between short‐term and long‐term plasticity. [ABSTRACT FROM AUTHOR]

One of the exceptional features of the van der Waals (vdW) ferroelectrics is the existence of stable polarization at a level of atomically thin monolayers. This ability to withstand a detrimental effect of the depolarization fields gives rise to complex domain configurations characterized, among others, by the presence of layered "antipolar" head‐to‐head (H‐H) or tail‐to‐tail (T‐T) dipole arrangements. In this study, tomographic piezoresponse force microscopy (TPFM) is employed to study the 3D polarization arrangement in vdW ferroelectric α‐In2Se3. Sequential removal of thin layers from the polar surface using the PFM tip reveals a complex 3D profile of the domain walls in the α‐In2Se3 crystals. Antiparallel domain layers stacked along the polar direction are also observed by PFM imaging of the non‐polar surfaces showing that H‐H and T‐T domain boundaries are commonly present in α‐In2Se3. Application of TPFM to the electrically written domains allows evaluation of their geometrical lateral‐to‐vertical size aspect ratio, which shows a strong prevalence for the sidewise expansion in comparison to the forward growth. Local I–V measurements reveal a strong polarization direction dependence of conductivity due to the modulation of the energy barrier height as corroborated by theoretical modeling. [ABSTRACT FROM AUTHOR]

One of the exceptional features of the van der Waals (vdW) ferroelectrics is the existence of stable polarization at a level of atomically thin monolayers. This ability to withstand a detrimental effect of the depolarization fields gives rise to complex domain configurations characterized, among others, by the presence of layered "antipolar" head‐to‐head (H‐H) or tail‐to‐tail (T‐T) dipole arrangements. In this study, tomographic piezoresponse force microscopy (TPFM) is employed to study the 3D polarization arrangement in vdW ferroelectric α‐In2Se3. Sequential removal of thin layers from the polar surface using the PFM tip reveals a complex 3D profile of the domain walls in the α‐In2Se3 crystals. Antiparallel domain layers stacked along the polar direction are also observed by PFM imaging of the non‐polar surfaces showing that H‐H and T‐T domain boundaries are commonly present in α‐In2Se3. Application of TPFM to the electrically written domains allows evaluation of their geometrical lateral‐to‐vertical size aspect ratio, which shows a strong prevalence for the sidewise expansion in comparison to the forward growth. Local I–V measurements reveal a strong polarization direction dependence of conductivity due to the modulation of the energy barrier height as corroborated by theoretical modeling. [ABSTRACT FROM AUTHOR]

Random networks offer fertile ground for achieving complexity and criticality, both crucial for an unconventional computing paradigm inspired by biological brains' features. In this work, characterizing and modeling different electrical transport regimes of self‐assemblies of silver nanowires (AgNWs) are focused. As percolation plays an essential role in such a scenario, a broad range of areal density coverage is examined. Close‐to‐percolation realizations (usually used to demonstrate neuromorphic computing capabilities) have high pristine resistance and require an electrical activation. Until now, highly conductive over‐percolated systems (commonly used in electrode fabrication technology) have not been thoroughly considered for hardware‐based neuromorphic applications, even though biological systems exhibit such an extremely high degree of interconnections. Here, it is shown that high current densities in over‐percolated low‐resistance AgNW networks induce a fuse‐type process, allowing a switching operation. Such electro‐fusing discriminates between weak and robust NW‐to‐NW links and enhances the role of filamentary junctions. Their reversible resistive switching enable different conductive paths exhibiting linear I–V features. Both percolation regimes are experimentally studied and proposed a model comprising two types of junctions that can describe, through numerical simulations, the overall behavior and observed phenomenology. These findings reveal a potential interplay of functionalities of neuromorphic systems and transparent electrodes. [ABSTRACT FROM AUTHOR]

Resistive switching memories have garnered significant attention due to their high‐density integration and rapid in‐memory computing beyond von Neumann's architecture. However, significant challenges are posed in practical applications with respect to their manufacturing process complexity, a leakage current of high resistance state (HRS), and the sneak‐path current problem that limits their scalability. Here, a mild‐temperature thermal oxidation technique for the fabrication of low‐power and ultra‐steep memristor based on Ag/TiOx/SnOx/SnSe2/Au architecture is developed. Benefiting from a self‐assembled oxidation layer and the formation/rupture of oxygen vacancy conductive filaments, the device exhibits an exceptional threshold switching behavior with high switch ratio exceeding 106, low threshold voltage of ≈1 V, long‐term retention of >104 s, an ultra‐small subthreshold swing of 2.5 mV decade−1 and high air‐stability surpassing 4 months. By decreasing temperature, the device undergoes a transition from unipolar volatile to bipolar nonvolatile characteristics, elucidating the role of oxygen vacancies migration on the resistive switching process. Further, the 1T1R structure is established between a memristor and a 2H‐MoTe2 transistor by the van der Waals (vdW) stacking approach, achieving the functionality of selector and multi‐value memory with lower power consumption. This work provides a mild‐thermal oxidation technology for the low‐cost production of high‐performance memristors toward future in‐memory computing applications. [ABSTRACT FROM AUTHOR]

Benefiting from powerful logic‐computing, higher packaging density, and extremely low electricity consumption, memristors are regarded as the most promising next‐generation of electric devices and are capable of realizing brain‐like neuromorphic computation. However, the design of emerging circuit devices based on memristors and their potential application in unconventional fields are very meaningful for achieving some tasks that traditional electronic devices cannot accomplish. Herein, a Cu/PEDOT:PSS‐PP:PVDF/Ti structured memristor is fabricated by using the polyvinylidene difluoride (PVDF) dopped biomaterial papaya peel (PP) and organic poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) heterojunction as functional layer, which can be switched among resistive switching, self‐rectification effect, and capacitive behavior by adjusting the voltage bias/scan rate. Through further fitting of the data and simulating interfacial group reactions, this work innovatively proposes a charge conduction mode of device driven by Fowler–Nordheim tunneling, complexation reactions, and PEDOT:PSS pore removal. Finally, the regular logic gate and adder circuits are constructed based on the fabricated memristor, while a fully adder‐based encryption unit is designed to realize data encryption and image reconstruction. This work renders memristor compatible with logic circuits, widening a path toward data encryption and information security. [ABSTRACT FROM AUTHOR]

In this study, we investigate the impact of O2 plasma treatment on the performance of Al/TaOX/Al-based resistive random-access memory (RRAM) devices, focusing on applications in neuromorphic systems. Comparative analysis using scanning electron microscopy and X-ray photoelectron spectroscopy confirmed the differences in chemical composition between O2-plasma-treated and untreated RRAM cells. Direct-current measurements showed that O2-plasma-treated RRAM cells exhibited significant improvements over untreated RRAM cells, including higher on/off ratios, improved uniformity and distribution, longer retention times, and enhanced durability. The conduction mechanism is investigated by current–voltage (I–V) curve fitting. In addition, paired-pulse facilitation (PPF) is observed using partial short-term memory. Furthermore, 3- and 4-bit weight tuning with auto-pulse-tuning algorithms was achieved to improve the controllability of the synapse weight for the neuromorphic system, maintaining retention times exceeding 103 s in the multiple states. Neuromorphic simulation with an MNIST dataset is conducted to evaluate the synaptic device. [ABSTRACT FROM AUTHOR]

This work reports the fabrication of a Silicon Oxide (SiOx) thin film (TF) via an electron beam evaporator on an Indium Tin Oxide (ITO) substrate for the application of a non-volatile memory device. The TF exhibits a high transmittance of ~ 79.7% in the visible range. The presence of capacitive memory was analyzed for the frequency range from 500 kHz to 1 MHz. An interface trap density of ~ 5.47 × 1011 eV−1 cm−2 was estimated at 1 MHz. In addition, the charge trapping density per unit area was ~ 1011 cm−2 at ± 9 V. Furthermore, the fabricated device's resistive switching (RS) analysis revealed a butterfly-shaped bipolar and forming-free behavior. The device exhibits a good retention time of up to 104 s and a stable endurance for 1000 repeated switching cycles. The conduction mechanisms: Ohmic conduction and Space Charge Limited Current conduction were responsible for the RS mechanisms in the fabricated device. The outcomes of our study suggest that the Au/SiOx/ITO TF device can be a promising candidate for integration into next-generation transparent, non-volatile memory devices. [ABSTRACT FROM AUTHOR]

As the key hardware of a brain-like chip based on a spiking neuron network (SNN), memristor has attracted more attention due to its similarity with biological neurons and synapses to deal with the audio signal. However, designing stable artificial neurons and synapse devices with a controllable switching pathway to form a hardware network is a challenge. For the first time, we report that artificial neurons and synapses based on multilayered HfOx/TiOy memristor crossbar arrays can be used for the SNN training of audio signals, which display the tunable threshold switching and memory switching characteristics. It is found that tunable volatile and nonvolatile switching from the multilayered HfOx/TiOy memristor is induced by the size-controlled atomic oxygen vacancy pathway, which depends on the atomic sublayer in the multilayered structure. The successful emulation of the biological neuron's integrate-and-fire function can be achieved through the utilization of the tunable threshold switching characteristic. Based on the stable performance of the multilayered HfOx/TiOy neuron and synapse, we constructed a hardware SNN architecture for processing audio signals, which provides a base for the recognition of audio signals through the function of integration and firing. Our design of an atomic conductive pathway by using a multilayered TiOy/HfOx memristor supplies a new method for the construction of an artificial neuron and synapse in the same matrix, which can reduce the cost of integration in an AI chip. The implementation of synaptic functionalities by the hardware of SNNs paves the way for novel neuromorphic computing paradigms in the AI era. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Ag/FWO/FTO memristive devices exhibit analogue-type bipolar resistive switching behavior. • The optimized device shows reliable non-volatile memory characteristics. • Statistical analysis reveals the better operational uniformity of the memristive devices. • The stable negative differential resistance (NDR) effect was observed in the devices. • Switching currents were modeled using Holt's Winter Exponential Smoothing technique. The memristors offer significant advantages as a key element in non-volatile and brain-inspired neuromorphic systems because of their salient features such as remarkable endurance, ability to store multiple bits, fast operation speed, and extremely low energy usage. This work reports the resistive switching (RS) characteristics of the hydrothermally synthesized iron tungstate (FeWO 4) based thin film memristive device. The detailed physicochemical analysis was investigated using Rietveld's refinement, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques. The fabricated Ag/FWO/FTO memristive device exhibits bipolar resistive switching (BRS) behavior. In addition, the devices exhibit negative differential resistance (NDR) at both positive and negative bias. The charge-flux relation portrayed the non-ideal or memristive nature of the devices. The reliability in the RS process was analyzed in detail using Weibull distribution and time series analysis techniques. The device exhibits stable and multilevel endurance and retention characteristics which demonstrates the suitability of the device for the high-density non-volatile memory application. The current conduction of the device was dominated by Ohmic and trap controlled-space charge limited current (TC-SCLC) mechanisms and filamentary RS process responsible for the BRS in the device. In a nutshell, the present investigations reveal the potential use of the iron tungstate for the fabrication of memristive devices for the non-volatile memory application. [ABSTRACT FROM AUTHOR]

Ca-doped BiFeO3/LaNiO3/LaAlO3 (BCFO/LNO/LAO) heterostructures have garnered significant interest due to their unique combination of ferroelectric, magnetic, and resistive switching properties due to interfaces and lattice mismatch/strain, leading to unique electronic properties. The roles of structural defects and oxygen vacancies are important in achieving the magnetic and electrical properties of BiFeO3-based heterostructures. By generating defects, swift heavy ion irradiation can lead to changes in the structural, optical, electrical, and magnetic properties of the materials. The Ca-doped BiFeO3 and LaNiO3 heterostructure was grown upon LAO substrates using the pulsed laser deposition technique, ensuring high-quality interfaces and controlled thicknesses. The heterostructures were irradiated with 80 MeV O+7 ions at various ion fluence levels (5 × 1010 ions/cm2 to 5 × 1012 ions/cm2). The structure and crystalline orientation of the thin films were confirmed through x-ray diffraction, while the surface morphology was measured using atomic force microscopy. Irradiation-induced modifications of the structural strain and surface morphology were investigated in the context of internal annealing effect and defect formation. The resistive switching (RS) properties of the proposed devices were assessed by I–V measurement with sweeping 0 → 5 V → 0 → − 5 V → 0, which shows that irradiation-induced defects play an important role in the electrical properties of the proposed heterostructure. Bipolar RS behavior was also verified with the conduction mechanism, indicating that the ohmic and space-charge-limited conduction mechanism plays an important role in irradiated BCFO/LNO/LAO heterostructures. Graphical representation of the defect formation and RS behavior due to varying ion fluence as a function of RMS roughness and strain. [ABSTRACT FROM AUTHOR]

Oxygen vacancy engineering in metal oxides is a propitious route to modulate their resistive switching properties for memory and neuromorphic applications. This review provides an account of the research works on tailoring RS behavior in oxide thin-film-based memristor devices by oxygen vacancy engineering. We discuss the recent research progress on controlling oxygen vacancy concentration in metal oxide thin films and its impact on their resistive switching properties for application in electronic memory and neuromorphic computing devices. [ABSTRACT FROM AUTHOR]

Recently, memristors have garnered widespread attention as neuromorphic devices that can simulate synaptic behavior, holding promise for future commercial applications in neuromorphic computing. In this paper, we present a memristor with an Au/Bi3.2La0.8Ti3O12 (BLTO)/ITO structure, demonstrating a switching ratio of nearly 103 over a duration of 104 s. It successfully simulates a range of synaptic behaviors, including long-term potentiation and depression, paired-pulse facilitation, spike-timing-dependent plasticity, spike-rate-dependent plasticity etc. Interestingly, we also employ it to simulate pain threshold, sensitization, and desensitization behaviors of pain-perceptual nociceptor (PPN). Lastly, by introducing memristor differential pairs (1T1R-1T1R), we train a neural network, effectively simplifying the learning process, reducing training time, and achieving a handwriting digit recognition accuracy of up to 97.19 %. Overall, the proposed device holds immense potential in the field of neuromorphic computing, offering possibilities for the next generation of high-performance neuromorphic computing chips.

Oxygen vacancy engineering in metal oxides is a propitious route to modulate their resistive switching properties for memory and neuromorphic applications. This review provides an account of the research works on tailoring RS behavior in oxide thin-film-based memristor devices by oxygen vacancy engineering. We discuss the recent research progress on controlling oxygen vacancy concentration in metal oxide thin films and its impact on their resistive switching properties for application in electronic memory and neuromorphic computing devices.

As a result of enormous progress in nanoscale electronics, interest in artificial intelligence (AI) supported systems has also increased greatly. These systems are typically designed to process computationally intensive data. Parallel processing neural network architectures are particularly noteworthy for their ability to process dense data at high speeds, making them suitable candidates for AI algorithms. Due to their ability to combine processing and memory functions in a single device, memristors offer a significant advantage over other electronic platforms in terms of area scaling efficiency and energy savings. In this study, single-layer and bilayer metal–oxide HfO x and TiO y memristor devices inspired by biological synapses were fabricated by pulsed laser and magnetron sputtering deposition techniques in high vacuum with different oxide thicknesses. The structural and electrical properties of the fabricated devices were analysed using x-ray reflectivity, x-ray photoelectron spectroscopy, and standard two-probe electrical characterization measurements. The stoichiometry and degree of oxidation of the elements in the oxide material for each thin film were determined. Moreover, the switching characteristics of the metal oxide upper layer in bilayer devices indicated its potential as a selective layer for synapse. The devices successfully maintained the previous conductivity values, and the conductivity increased after each pulse and reached its maximum value. Furthermore, the study successfully observed synaptic behaviours with long-term potentiation, long-term depression (LTD), paired-pulse facilitation, and spike-timing-dependent plasticity, showcasing potential of the devices for neuromorphic computing applications. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) could create opportunities of modulating resistive switching behaviors due to their unique electrical performance. Here, CQDs are introduced to enhance switching uniformity and magnetic properties in Co 3 O 4 thin film memory devices. Compared with the pure Co 3 O 4 -based device, the device with CQDs exhibited better performance, such as a reduced initialization voltage, uniform distribution of Set and Reset voltages, stable endurance behavior, and enhanced magnetization performance. The fitting results of current-voltage curves showed that the low-resistance states and high-resistance states of the devices obey Ohmic conduction and Schottky emission, respectively. The improvement in resistive switching properties is ascribed to the formation and rupture of confined conductive filaments due to that CQDs enhanced the local electric field, which can efficiently guide the filament growth and suppress the randomness of filament growth. Magnetization modulation associated with resistive switching involves in the variation of oxygen vacancies concentration and the conversion between Co2+ and Co3+. The present study exhibits an effective path to enhance resistive switching and magnetic properties, which shows promising application to design multifunctional electro-magnetic integrated devices. [ABSTRACT FROM AUTHOR]

Hydrothermally grown NiO nanoflakes have been investigated here for their resistive switching (RS) and photoabsorption characteristics. The formation and disruption of the conducting filament (CF) under an applied external electric field leads to bistable resistive switching in the grown NiO nanoflakes. Comprehensive investigations of the I–V behaviour show that the formation and rupturing of the CF depend on the concentration of the metallic Ni. Interestingly, photoabsorption response demonstrates a nearly similar behaviour in UV and visible regions for nanoflakes grown at low reaction time, but an enhanced UV response for the flakes obtained at larger reaction times. These nanoflakes displaying multifunctional properties of photoabsorption and RS behaviour, that can be modulated with reaction time, are attractive for optoelectronic, electrochromic and RS-based memory applications. [ABSTRACT FROM AUTHOR]

The emerging nonvolatile memory, three-dimensional vertical resistive random-access memory (VRRAM), inspired by the vertical NAND structure, has been proposed to replace NAND flash memory which has reached its integration limit. To improve the vertical ionic diffusion occurring in the conventional VRRAM structure, we propose a Pt/HfO2/TiO2/Ti self-aligned VRRAM with physically confined switching cells through sidewall thermal oxidation. We achieved stable bipolar switching, endurance (>104 cycles), and retention (>104 s) responses, and improved the interlayer leakage current issue through a distinctive self-aligned structure. Additionally, we elucidated the switching mechanism by analyzing current levels concerning ambient temperature. To utilize VRRAM for neuromorphic computing, the biological synaptic functions are emulated by applying pulse stimulation to the synaptic cell. The weight modulation of biological synapses is demonstrated based on potentiation, depression, spike-rate-dependent plasticity, and spike-timing-dependent plasticity. Additionally, we improve the pattern recognition rate by creating a linear conductance modulation with an incremental pulse train in pattern recognition simulations. The stable electrical characteristics and implementation of various synaptic functions demonstrate that self-aligned VRRAM is suitable for neuromorphic systems as a high-density synaptic device. [ABSTRACT FROM AUTHOR]

Abstract Two-dimensional (2D) materials have emerged as promising building blocks for next generation memristive devices, owing to their unique electronic, mechanical, and thermal properties, resulting in effective switching mechanisms for charge transport. Memristors are key components in a wide range of applications including neuromorphic computing, which is becoming increasingly important in artificial intelligence applications. Crossbar arrays are an important component in the development of hardware-based neural networks composed of 2D materials. In this paper, we summarize the current state of research on 2D material-based memristive devices utilizing different switching mechanisms, along with the application of these devices in neuromorphic crossbar arrays. Additionally, we discuss the challenges and future directions for the field.

Resistive random‐access memory (RRAM) stands out as a promising memory technology due to its ease of operation, high speed, affordability, exceptional stability, and potential to enable smaller memory devices with sizes under 10 nm. This has drawn significant attention, with atomic layer deposition (ALD) emerging as an ideal technology to tackle the challenges of nanoscale fabrication in the micro‐ and nanomanufacturing industry. ALD offers technological advantages such as functional multiple‐layer stacking, doping capabilities, and incorporating oxygen reservoirs or reactive layers. These factors contribute to achieving more intriguing, stable, and reliable nonvolatile resistance switching behaviors in RRAM. Specifically, ALD greatly benefits RRAM, that relies on the valence change mechanism, where high‐k transition metal oxides are commonly used as switching materials, and precise control over oxygen vacancies is achievable. This review provides a comprehensive overview of ALD films used in RRAM, delves into resistive switching properties and microscopic mechanisms in binary and ternary oxides and nitrides, and explores the impact of ALD‐prepared electrodes. Furthermore, the current status and future prospects of ALD‐based RRAM are highlighted, which is poised to catalyze further advancements in the fields of information storage and neural networks. [ABSTRACT FROM AUTHOR]

The current memory system is facing obstacles to improvement, and ReRAM is considered a powerful alternative. All‐inorganic α‐CsPbI3 perovskite‐based ReRAM working by electrochemical mechanism is reported, but the electrochemically active electrode raised difficulty in long‐term stable operation, and bulk α‐CsPbI3 device can not show resistive switching behavior with an inert metal top electrode. Herein, by making the α‐CsPbI3 into QDs and applying it to the device with inert Au as the top electrode, the devices working by valence change mechanism are successfully fabricated. The large surface‐to‐volume ratio made an abundant amount of iodine vacancies and facile migration of vacancies allowed the device to work by valence change mechanism. The devices show reliable electrical characteristics, 800 cycles endurance and retention for over 4 × 104 s, and air stability for 1 month. This work demonstrates that applying the QDs can improve the stability and enable a new type of working mechanism in ReRAM. [ABSTRACT FROM AUTHOR]

Resistive switching memory devices based on organic materials are intriguing. These devices are biodegradable and nontoxic to living organisms. In this work, using euphorbia cotinifolia plant extract was investigated for its applicability as an active layer of a resistive switching memory device consisting of silver top electrode and indium-doped tin oxide bottom electrode. This study selected Euphorbia cotinifolia because it is a common, prolific and simple-to-grow plant in many South African homes. When the euphorbia cotinifolia plant is broken, an extract resembling milk is emitted. This extract was collected directly onto the bottom electrode, which was then dried at ambient temperature. For top electrode, silver paste was applied. The entire fabrication process was devoid of heat and electricity. The fabricated device showed impressive properties such as memory hysteresis with ON/OFF = 5 , endurance of over 3 2 write/erase cycles, and an impressive retention of ≥ 1 0 3   s. Therefore, this system may be a candidate for a nonvolatile and disposable memory device. [ABSTRACT FROM AUTHOR]

This work investigates the resistive switching in InGaZnO (IGZO) memristors with different electrodes, including Cu, Au, Ag, and Ti. Cu electrode device possesses the lowest switching voltage, while Au electrode device exhibits a good endurance of 100 repeated cycling tests. Ag electrode device shows a mediocre performance. As for the Ti electrode device, it has a relatively larger on/off ratio but a highest switching voltage. Corresponding mechanisms for the current conduction are explored, and models based on the experimental results are proposed to explain the RS mechanisms. Additionally, multi-value storage potential of Cu electrode device is also investigated by varying compliance current. [ABSTRACT FROM AUTHOR]

In this study, bioengineered and biosynthesized elastin-like polypeptide (ELP) was adopted for a non-volatile memory resistive switching device or a memristor. The ELP mimicked from elastin of mammal was synthetically produced in polypeptide by Escherichia coli gene recombination. They were composed of a repeating pentapeptide sequence having [Val-Pro-Gly-Val-Gly]32 sequence for bioelectronic devices with ELP showing multiple electrical resistance states between a high resistance state and a low resistance state through an applied electrical field. In addition, the ELP-coated 5-nm gold nanoparticles (Au NPs) layer was also to be biomaterials used for nanobiohybrid memristive devices. Simple metal–insulator–metal device structure and lateral electrode device with ELP layer on 5-nm Au NPs could show neuromorphic adaptive current–voltage (I–V) behavior and electrical stimulus-induced potentiation and depression in a hydrogel state. In addition, with an introduction of a neurotransmitter cortisol's specific antibody, a preliminary sensing protocol was also examined with the nanobiohybrid device. Therefore, the introduction of ELP into neuromorphic device is regarded as the cornerstone for the development of biocompatible bioelectronic devices that can be integrated into human bionics for future artificial neuromorphic format. [ABSTRACT FROM AUTHOR]

We report on capacitance and current voltage nonlinearities to understand the resistive switching (RS) behavior in metal–insulator–metal (MIM) capacitors and its dependence on electrode material. Hafnium oxide (HfO2) thin films were deposited at 350°C on various electrode materials, including platinum (Pt), tungsten (W), aluminum copper (AlCu), and titanium nitride (TiN). The current–voltage (I–V) sweep measurements were analyzed using the trap-controlled space-charge-limited conduction mechanism. The results were correlated to the first-principles calculations of the HfO2/M heterostructures using the projector-augmented wave coupled to the generalized gradient approximation. The band structure, density of states, and partial density of states were calculated and interpreted. The band offset for the metal–oxide interfaces was determined using the Van de Walle and Martin model. Accordingly, we demonstrated that the dissipation energy of the MIM structures decreased with increasing valence band offset between the metal electrode and oxide. The link between I–V nonlinearity and capacitance–voltage variation was established through the concept of average electrostatic potential. We demonstrated that the observed C–V nonlinearity decreased with increasing potential discontinuity. These findings have promising implications for the design and optimization of future resistive random-access memory devices. [ABSTRACT FROM AUTHOR]

Memristors are a candidate device for artificial neural systems due to their excellent conductance‐regulation ability and potential to simulate the characteristics of biological synapses. This study fabricated a Pt/TaOx/TiOy/Ti analog artificial synapse memristor that exhibits excellent multilevel storage property with a large on/off ratio of ≈660 times. The dynamic resistive switching mechanism is well expounded and validated by the reset stopping voltage dependent Schottky fitting results. Moreover, the essential biological synaptic characteristics such as long‐term potentiation/depression (LTP/D) and paired‐pulse facilitation (PPF) are successfully mimicked with a low pulse energy consumption of 12.69 nJ. A neuromorphic network constructed on the enhanced symmetry and linearity of conductance for this Pt/TaOx/TiOy/Ti memristive device can achieve 92.45% accuracy in recognizing handwritten pattern. These results demonstrate a significant potential for application Pt/TaOx/TiOy/Ti memristor in non‐volatile memory and bioinspired neuromorphic systems. [ABSTRACT FROM AUTHOR]

In this paper, using a combination of pulse testing measurements and piezoresponse force microscopy (PFM), an investigation of the polarization reversal behavior and the accompanying resistive switching in the Al0.72Sc0.28N thin film capacitors is reported. The obtained results reveal a transition from the nucleation‐limited switching (NLS) in the low field range toward the more uniform switching described by the Kolmogorov–Avrami–Ishibashi (KAI) model in the high field range. It is found that the Al0.72Sc0.28N capacitors exhibit an unusually steep change in the switching time– it decreases by five orders of magnitude with a moderate increase of the applied field. This feature is caused by a significantly higher activation field value (≈126 MV cm−1) in comparison with the conventional perovskite ferroelectrics. PFM visualization of the field‐induced domain dynamics has allowed the evaluation of the nucleation rate and domain wall velocity. Furthermore, capacitors in the polydomain state generated by partial switching of polarization exhibit a significant (up to two orders of magnitude) increase in the steady‐state conductance. This effect is likely caused by the injection of strongly inclined conducting 180° domain walls. Resistance tunability offers additional functionalities to the Al1‐xScxN devices where conductive domain walls are used as active elements. [ABSTRACT FROM AUTHOR]

In the strive for energy efficient computing, many different neuromorphic computing and engineering schemes have been introduced. Nanoparticle networks (NPNs) at the percolation threshold have been established as one of the promising candidates, e.g., for reservoir computing because among other useful properties they show self‐organization and brain‐like avalanche dynamics. The dynamic resistance changes trace back to spatio‐temporal reconfigurations in the connectivity upon resistive switching in distributed memristive nano‐junctions and nano‐gaps between neighboring nanoparticles. Until now, however, there has not yet been any direct imaging or monitoring of current paths in NPN. In this study, an NPN comprising of Ag/CxOyHz core/shell and Ag nanoparticles at the percolation threshold is reported. It is shown that this NPN is within a critical regime, exhibiting avalanche dynamics. To monitor in situ the evolving current paths in this NPN, active voltage contrast and resistive contrast imaging are used complementarily. Including simulations, the results provide experimental insight toward understanding the complex current response of the memristive NPN. As such, this study paves the way toward an experimental characterization of dynamic reorganizations in current paths inside NPN, which is highly relevant for validating and improving simulations and finally establishing a deeper understanding of switching dynamics in NPNs. [ABSTRACT FROM AUTHOR]

The paper reveals the influence of Li, B and the composition of metal contacts on the processes of resistive switching in memristive structures M/NC/D/M. After field exposure in structures Cu/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cu/(Co50Fe50)x(LiNbO3)100–x/d-LiNbO3/Cu/sitall and Cu/(Co40Fe40B20)x(SiO2)100–x/d LiNbO3/Cu/sitall at x < 13 was detected a residual voltage (up to 16 mV) due to the electromigration of Li ions, that leading to a "reversible" type of VAC hysteresis and instability of the time dependencies of induced resistive states. In the structures of Cu/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cr/Cu/Cr/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall containing B, the residual voltage is reduced by formation of chemical compounds B with percolated Li atoms. When limiting the electromigration of Li ions, the main mechanism of resistive switching is the processes of electromigration of oxygen vacancies in the dielectric oxide layer. Suppression of residual voltage in the Cr/Cu/Cr/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall structure due to the introduction of a Cr buffer layer that does not dissolve Li leads to the absence of bipolar resistive switching in these structures. [ABSTRACT FROM AUTHOR]

The key elements of neuromorphic computing systems (NCS) are memristors—resistors with a memory effect—that can be used for simultaneous processing and storage of information. It is promising to create them in crossbar geometry, where memristors are located at the intersections of the transverse electrode buses. In this work, the influence of the area and geometry of contacts on the main memristive characteristics of parylene-based structures is investigated. The results obtained indicate the independence of such memristive characteristics as the switching voltage into the low-resistance (Uset) and high-resistance states (Ureset), as well as the resistance of the samples in the low-resistance (Ron) state, from the contact area. At the same time, resistances in the high-resistance (Roff) state increase with decreasing area, which confirms the single-filament model of resistive switching, and also makes it possible to increase the window of resistance in such structures. [ABSTRACT FROM AUTHOR]

The results of the research on the resistive switching in Pt/HfO2/HfOxNy/TiN, Pt/HfO2/TaOxNy/TiN and Pt/Al2O3/HfO2/TaOxNy/TiN structures are presented. Active layers of the structures were deposited by atomic layer deposition. The formation of conductive filaments in all three structures was demonstrated using conductive atomic force microscopy. A full cycle of resistive switching with a microscope probe in these structures was also demonstrated. The properties of filaments formed at different voltages were studied, and the distributions of the filament density by conductivity and size were presented. The characteristics of the studied structures were compared. It appears that the Pt/Al2O3/HfO2/TaOxNy/TiN structure has the greatest potential for resistive random-access memory application. [ABSTRACT FROM AUTHOR]

Resistive Random Access Memory (RRAM) is a prominent contender in the realm of emerging non-volatile memory technologies owing to its numerous advantages like simple structure, low power usage, high speed, and exceptional scalability. In the current study, RRAM device was fabricated using tantalum oxide (TaOx) as a resistive switching insulating oxide layer, which was sandwiched between two conducting electrodes, namely Ag and ITO. RF magnetron sputtering was used to deposit the insulating layer of TaOx at room temperature on the ITO substrate. Further, X-ray reflectivity and hard X-ray photoelectron spectroscopy analyses were conducted to find the thickness, roughness, and elemental composition of the deposited TaOx films. Using a semiconductor analyzer, the RRAM cell's first DC switching characteristics were determined. The data acquired exhibited a resistance ratio (RHRS/RLRS) of 120 showing a good distinction between the two-resistance states. Additionally, a thorough investigation was conducted to examine the electrical conduction mechanism occurring inside the fabricated RRAM device. [ABSTRACT FROM AUTHOR]

In this study, the resistive switching phenomena in TiN/Ti/HfO2/Ti metal–insulator–metal stacks is investigated, mainly focusing on the analysis of set and reset transitions. The electrical measurements in a wide temperature range reveal that the switching transitions require less voltage (and thus, less energy) as temperature rises, with the reset process being much more temperature sensitive. The main conduction mechanism in both resistance states is Space-charge-limited Conduction, but the high conductivity state also shows Schottky emission, explaining its temperature dependence. Moreover, the temporal evolution of these transitions reveals clear differences between them, as their current transient response is completely different. While the set is sudden, the reset process development is clearly non-linear, closely resembling a sigmoid function. This asymmetry between switching processes is of extreme importance in the manipulation and control of the multi-level characteristics and has clear implications in the possible applications of resistive switching devices in neuromorphic computing. [ABSTRACT FROM AUTHOR]

The paper reveals the influence of Li, B and the composition of metal contacts on the processes of resistive switching in memristive structures M/NC/D/M. After field exposure in structures Cu/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cu/(Co50Fe50)x(LiNbO3)100–x/d-LiNbO3/Cu/sitall and Cu/(Co40Fe40B20)x(SiO2)100–x/d LiNbO3/Cu/sitall at x < 13 was detected a residual voltage (up to 16 mV) due to the electromigration of Li ions, that leading to a "reversible" type of VAC hysteresis and instability of the time dependencies of induced resistive states. In the structures of Cu/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cu/sitall, Cr/Cu/Cr/(Co40Fe40B20)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall containing B, the residual voltage is reduced by formation of chemical compounds B with percolated Li atoms. When limiting the electromigration of Li ions, the main mechanism of resistive switching is the processes of electromigration of oxygen vacancies in the dielectric oxide layer. Suppression of residual voltage in the Cr/Cu/Cr/(Co50Fe50)x(LiNbO3)100–x/s-LiNbO3/Cr/Cu/Cr/sitall structure due to the introduction of a Cr buffer layer that does not dissolve Li leads to the absence of bipolar resistive switching in these structures. [ABSTRACT FROM AUTHOR]

Memristors, being prospective work‐horses of future electronics offer various types of memory (volatile and nonvolatile) along with specific computational functionalities. Further development of memristive technologies depends on the availability of suitable materials. These materials should be easily available, stable, and preferably of low toxicity. Commonly used materials are lead halide perovskites, however, they are highly toxic and unstable under ambient conditions. Therefore a novel material is developed on the basis of bismuth iodide. In reaction with butylammonium iodide, it yields a novel compound, butylammonium iodobismuthate (BABI). Here, a diffusive memristor is introduced based on this compound and evaluates its memristive and neuromorphic properties. In contrast to nonvolatile memristors, the BABI memristors exhibit diffusive dynamics, which enable them to store the information only for short periods of time. This property is utilized to mimic the short‐term synaptic plasticity described by the leaky integrate‐and‐fire model of a biological neuron. Combined with high switching uniformity and self‐rectifying behavior, these devices show high classification accuracy for MNIST handwritten datasets, paving the way for their application in neuromorphic computing systems. [ABSTRACT FROM AUTHOR]

Herein we report on a facile sol-gel spin-coating technique to fabricate ZnO thin films that grow preferentially along the (002) plane on FTO substrates. By employing the magnetron sputtering technique to deposit a tungsten (W) top metal electrode onto these ZnO thin films, we successfully realize a W/ZnO/FTO memory device that exhibits self-rectifying and forming-free resistive switching characteristics. Notably, the as-prepared device demonstrates impressive nonvolatile and bipolar resistive switching behavior, with a high resistance ratio (RHRS/RLRS) exceeding two orders of magnitude at a reading voltage of 0.1 V. Moreover, it exhibits ultralow set and reset voltages of approximately +0.5 V and −1 V, respectively, along with exceptional durability. In terms of carrier transport properties, the low resistance state of the device is dominated by ohmic conduction, whereas the high resistance state is characterized by trap-controlled space-charge-limited current conduction. This work highlights the potential of the ZnO-based W/ZnO/FTO memory device as a promising candidate for future high-density nonvolatile memory applications. [ABSTRACT FROM AUTHOR]