Type Of Resistive Switching Research Articles

Three types of resistive switching in ferroelectric Hf0.5Zr0.5O2 films mediated by polarization reversal and oxygen vacancy migration

Three types of resistive switching in ferroelectric Hf0.5Zr0.5O2 films mediated by polarization reversal and oxygen vacancy migration

Origin identification and accuracy control of electrode interface-related asymmetrical hysteresis in light-controlled resistive switching of single CH3NH3PbI3 micro/nanowire

Remarkable photoresponse and resistive switching (RS) performance of CH3NH3PbI3 has garnered significant attention. However, precise control over the emergence and polarity of hysteresis loops in bipolar RS remains challenging. Herein, we constructed an individual CH3NH3PbI3 micro/nanowire device configured with two symmetrical Ag electrodes and asymmetrically modulated their electrode interface states by encapsulating only one electrode. We propose an electrode interface-related RS mechanism to modulate the hysteresis features and achieve different types of high-performance light-controlled RS. In an unpacked electrode interface, large potential induces oxidation of Ag to AgI with high resistivity under light and trace moisture, resulting in a high-resistance state. On the other hand, in a packed electrode interface, large potential triggers hole injection into interface traps with the assistance of light, resulting in a low-resistance state. Additionally, reversible Ag/AgI oxidation/reduction-related negative RS and hole injection/ejection-associated positive RS lead to bipolar RS, accompanied by clockwise and counterclockwise hysteresis loops in two directions. Furthermore, performance is entirely determined by illumination intensity and bias amplitude, achieving photomemory. This work unveils the influence of moisture and illumination on electrode interface and the actual origin of hysteresis, while also precisely controlling photomemory performance. Therefore, it provides a specific strategy for designing high-performance light-controlled RS with nonvolatile photomemory.

Nonvolatile resistive switching in interface-dominated memristors utilizing two-dimensional Cs2Pb(SCN)2Br2 perovskite films

In this study, all-inorganic two-dimensional (2D) perovskite Cs2Pb(SCN)2Br2 was employed in a thin-film vertical structure prototype memristor. The device consisted of a Cs2Pb(SCN)2Br2 film prepared through solution approach, sandwiched between an Ag electrode and a TiO2/FTO substrate bottom electrode. Two types of resistive switching (RS) behaviors were observed within a single device at different temperatures. At room temperature, the dominant control mechanism was the interface Schottky barrier, whereas at higher temperatures, the primary driving force shifted to the conductive channel. The device has an on/off ratio exceeding 103 under the interface control mechanism. The migration of mobile bromine vacancies within the Cs2Pb(SCN)2Br2 film, whose concentration was enhanced by the infiltration and reaction of the Ag active electrode within the Cs2Pb(SCN)2Br2 film, is proposed to be the root cause for both types of RS characteristics. These findings offer insights into the potential application of 2D Cs2Pb(SCN)2Br2 perovskite in RS memory devices.

Vacancy-Engineered Nickel Ferrite Forming-Free Low-Voltage Resistive Switches for Neuromorphic Circuits.

Innovations in resistive switching devices constitute a core objective for the development of ultralow-power computing devices. Forming-free resistive switching is a type of resistive switching that eliminates the need for an initial high voltage for the formation of conductive filaments and offers promising opportunities to overcome the limitations of traditional resistive switching devices. Here, we demonstrate mixed charge state oxygen vacancy-engineered electroforming-free resistive switching in NiFe2O4 (NFO) thin films, fabricated as asymmetric Ti/NFO/Pt heterostructures, for the first time. Using pulsed laser deposition in a controlled oxygen atmosphere, we tune the oxygen vacancies together with the cationic valence state in the nickel ferrite phase, with the latter directly affecting the charge state of the oxygen vacancies. The structural integrity and chemical composition of the films are confirmed by X-ray diffraction and hard X-ray photoelectron spectroscopy, respectively. Electrical transport studies reveal that resistive switching characteristics in the films can be significantly altered by tuning the amount and charge state of the oxygen vacancy concentration during the deposition of the films. The resistive switching mechanism is seen to depend upon the migration of both singly and doubly charged oxygen vacancies formed as a result of changes in the nickel valence state and the consequent formation/rupture of conducting filaments in the switching layer. This is supported by the existence of an optimum oxygen vacancy concentration for efficient low-voltage resistive switching, below or above which the switching process is inhibited. Along with the filamentary switching mechanism, the Ti top electrode also enhances the resistive switching performance due to interfacial effects. Time-resolved measurements on the devices display both long- and short-term potentiation in the optimized vacancy-engineered NFO resistive switches, ideal for solid-state synapses achieved in a single system. Our work on correlated oxide forming-free resistive switches holds significant potential for CMOS-compatible low-power, nonvolatile resistive memory and neuromorphic circuits.

A Bifunctional Memristor Enables Multiple Neuromorphic Computing Applications

AbstractAs a promising building block of the emerging neuromorphic computing hardware, memristive structures with multi‐functionalities are highly desired to implement diversified computing applications in a single device. However, the demonstration of such multi‐functional structures remains limited. In this work, an Ag/GeS/Pt‐based bifunctional memory structure with both long‐term and short‐term memristive behaviors is reported, enabling multiple neuromorphic computing applications in a single device. It is found that the unexpected short‐term switching in Ag/GeS/Pt can not only be used to simulate learning/relearning and forgetting behavior but can also be implemented for reservoir computing. While for long‐term switching memristive behavior, its application is demonstrated as the traditional memory. The work reveals a novel coexistence of the two types of resistive switching, shedding light on various neuromorphic computing applications such as reservoir computing and traditional memory realized in a single memristive device.

Investigation of resistive switching in Ag/Ge/Si(001) stack by conductive atomic force microscopy

We report on an experimental study of resistive switching (RS) of individual dislocations in Ag/Ge/Si(001) memristors by combined grazing incidence ion sputtering of the Ag electrodes and application of Conductive Atomic Force Microscopy to provide an electrical contact to individual Ag-filled dislocations in the Ge layer. Two types of RS were observed corresponding to two different RS mechanisms: (i) drift of Ag+ ions inside the dislocation cores and (ii) RedOx reactions in residual GeO x in the etch pits on the Ge layer surface.

Transition between bipolar and abnormal bipolar resistive switching in amorphous oxides with a mobility edge

Resistive switching is an important phenomenon for future memory devices such as resistance random access memories or neuronal networks. While there are different types of resistive switching, such as filament or interface switching, this work focuses on bulk switching in amorphous, binary oxides. Bulk switching was found experimentally in different oxides, for example in amorphous gallium oxide. The forms of the observed current–voltage curves differ, however, fundamentally. Even within the same material, both abnormal bipolar and normal bipolar resistive switching were found. Here, we use a new drift–diffusion model to theoretically investigate bulk switching in amorphous oxides where the electronic conductivity can be described by Mott’s concept of a mobility edge. We show not only that a strong, non-linear dependence of the electronic conductivity on the oxygen content is necessary for bulk switching but also that changing the geometry of the memristive device causes the transition between abnormal and normal bipolar switching.

Subthreshold firing in Mott nanodevices.

Resistive switching, a phenomenon in which the resistance of a device can be modified by applying an electric field1-5, is at the core of emerging technologies such as neuromorphic computing and resistive memories6-9. Among the different types of resistive switching, threshold firing10-14 is one of the most promising, as it may enable the implementation of artificial spiking neurons7,13,14. Threshold firing is observed in Mott insulators featuring an insulator-to-metal transition15,16, which can be triggered by applying an external voltage: the material becomes conducting ('fires') if a threshold voltage is exceeded7,10-12. The dynamics of this induced transition have been thoroughly studied, and its underlying mechanism and characteristic time are well documented10,12,17,18. By contrast, there is little knowledge regarding the opposite transition: the process by which the system returns to the insulating state after the voltage is removed. Here we show that Mott nanodevices retain a memory of previous resistive switching events long after the insulating resistance has recovered. We demonstrate that, although the device returns to its insulating state within 50 to 150nanoseconds, it is possible to re-trigger the insulator-to-metal transition by using subthreshold voltages for a much longer time (up to several milliseconds). We find that the intrinsic metastability of first-order phase transitions is the origin of this phenomenon, and so it is potentially present in all Mott systems. This effect constitutes a new type of volatile memory in Mott-based devices, with potential applications in resistive memories, solid-state frequency discriminators and neuromorphic circuits.

Methods for distinguishing Mott transitions from Anderson transitions

Metal-insulator transitions (MITs) (resistive switching) is an important research area. The underlying mechanisms are complex and have not been completely understood. Two or more different transitions can be induced simultaneously. Thus, to better understand the mechanisms of MITs for a specific material, it is necessary to design criteria for differentiating between transition mechanisms. Here, we studied resistive switching in Mott and Anderson insulators. These insulators (exhibiting Mott and Anderson resistive switching) were distinguished based on their properties. In Anderson insulators, electron states are localised at the Fermi level without a band gap, and resistivity is given by ln ρ = AT-1/4 within a certain range of temperatures. However, in Mott insulators, the Fermi level features a band gap, and ln ρ does not linearly depend on T-1/4. Therefore, optical conductivity, which can predict materials' band gaps and resistivity-temperature characteristics, can be used for distinguishing between Mott and Anderson types of resistive switching.

Influence of polarity of set voltage on the properties of conductive filaments in NiO based nonvolatile memory device

In this paper, we realize the coexistence of bipolar and unipolar resistive switching (RS) in one Pt-Ir/NiO/TiB1+δ cell. The types of RS are controlled by polarity of set voltage and are free from the current compliance. Based on this coexistence, the set voltage and characters of filaments formed in RS are studied. The results show that the types of filaments also show polarity dependence on the set voltage. The positive set voltage can induce metallic filaments while the negative set voltage can result in semiconductor filaments. It reveals that the distribution of magnitude of set voltage shows abnormal polarity dependence in our devices. The combination the theory of interaction between oxygen vacancy defects and one-carrier impact ionization theory of breakdown account for these results. The influence of filament properties on RS types is also discussed.

Resistive memory switching in layered oxides: AnBnO3n+2 perovskite derivatives and Bi2Sr2CaCu2O8+δ high‐Tc superconductor

AbstractResistive memory switching was investigated in titanates and niobates of the type AnBnO3n+2 and in the high‐Tc superconductor Bi2Sr2CaCu2O8+δ. We studied the switching by current injection perpendicular to the layers. Both dc and pulsed measurements were performed. Out‐of‐plane transport properties were investigated by measurements of the resistance and current–voltage characteristics (IVs) vs. temperature for different resistive states. The critical temperature of superconducting transition and the critical current of intrinsic Josephson junctions were also analyzed for different resistive states in Bi2Sr2CaCu2O8+δ. The resistive memory switching was explained in terms of doping of the conducting layers, which is induced by trapped charges in the insulating layers. The charged insulating layers act as a floating gate and reduce or increase the carrier concentration in the conducting layers, respectively. We found that all studied materials demonstrate a different type of non‐persistent resistive switching at low temperatures. This type of switching shows up in a specific form of current–voltage characteristics with a pronounced back‐bending often called s‐shaped IV. Both types of resistive switching with and without memory effect were analyzed in terms of electron overheating. We examine the role of hot electrons and discuss additional factors, which might lead to persistent resistive states.

Electric‐Field‐Induced Resistive Switching in a Family of Mott Insulators: Towards a New Class of RRAM Memories

Flash memories (USB portable drives) are close to their miniaturization limits. The ultimate evolution of such devices is believed to exploit different concepts such as electronic phase transitions. Here we show that an electric field can trigger fast resistive switching in the fragile Mott insulators AM4X8 (A= Ga, Ge ; M = V, Nb, Ta; X = S, Se). This new type of resistive switching could lead to a new class of resistive random access memory (RRAM) with fast writing/erasing times (down to 50 ns) and resistance ratios ΔR/R of the order of 25% at room temperature. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.