Nanoionic Resistive‐Switching Devices

Abstract

devices have opened up promising opportunities for electronic circuit applications beyond energy storage. One representative example is ionic resistive-switching (RS) devices (also called memristive devices or memristors), [3][4][5] which can be used as a nonvolatile memory element due to its excellent performance such as high switching speed (<1 ns), [6] good retention (>10 years), [7] good endurance (>10 9 ), [8] as well as high device scalability. [9] The RS effect refers to the phenomenon that the resistance of a dielectric thin film, typically sandwiched between two electrodes, can be reversibly modulated by an electric field. [2] In ionic RS devices, the mechanism originates from the rearrangement of atoms/ions in the dielectric thin film through ionic drift/ diffusion and electrochemical processes that lead to the formation/rupture of nanoscale conductive paths (filaments) between the two electrodes. [10] Controlling these internal ionic processes will enable the design and implementation of better engineered devices with improved performance and reliability. Additionally, recent studies show that the internal ionic processes during RS can be used to faithfully emulate many biological effects that are critical for learning and memory, allowing efficient neuromorphic systems to be implemented using solid-state devices and networks. [11][12][13] Controlled ionic processes can also be used to directly modify the composition and/or structure of the material itself at the atomic scale, allowing new nanostructures to be built on the fly, in a reconfigurable fashion.In this review, we will first discuss the switching mechanism of ion-induced RS (memristive) effects in nanoscale solid-state thin films, followed by discussions on controlling and utilization of the ionic effects to implement biological synaptic functions, and to reduce device variation and improve device stability. New concepts of material tuning enabled by controlled ionic process will be introduced at the end. Ion-Induced RS EffectSo far, ion-driven RS effects have been observed in a large variety of materials, ranging from oxides, halides, to chalcogenides, etc. [2,[13][14][15] Based on the types of ions involved during the RS process, the switching mechanism can be divided to three categories: cation-driven RS effects, anion-driven RS effects, and cation and anion jointly driven RS effects.Advances in the understanding of nanoscale ionic processes in solid-state thin films have led to the rapid development of devices based on coupled ionic-electronic effects. For example, ion-driven resistive-switching (RS) devices have been extensively studied for future memory applications due to their excellent performance in terms of switching speed, endurance, retention, and scalability. Recent studies further suggest that RS devices are more than just resistors with tunable resistance; instead, they exhibit rich and complex internal ionic dynamics that equip them with native information-processing capabilities, particularly in the temporal domain. RS effec...

Memristor networks for real-time neural activity analysis

“…1), the memristor device serving as the reservoir plays a key role. A memristor is essentially a two-terminal resistive device whose conductance can be modulated by an electrical input, normally through the redistribution of ions [16][17][18][19] . For example, under an electric field during the SET process, the migration of oxygen ions in oxide films can generate oxygen vacancies (V O s) acting as n-type dopants to form local conduction channels and increase the device conductance.…”

“…More specifically, dynamic memristors with inherent short-term memory effects have recently been successfully utilized as reservoirs for temporal data processing 15 . Beyond benefits such as having a simple device structure that allows easy fabrication and integration, the characteristics of a memristor device can be tailored by carefully engineering the switching material and optimizing the device structure [16][17][18][19] , allowing one to develop memristors with desired operation voltages and dynamics for different applications. To this end, memristor-based RC systems offer intriguing opportunities to be integrated with the neural probe for on-site, real-time neural signal processing.…”

Perspectives on Atomic-Scale Switches for High-Frequency Applications Based on Nanomaterials

“…There exist other types of memristors which are good microwave switches, such as nano-ionic memristors [ 11 ]. Cations, anions or a combination of both can be used for the implementation of such memristors.…”

Enhancing Reliability of Studies on Single Filament Memristive Switching via an Unconventional cAFM Approach

“…An important stimulus to this field came in 2008 [1], where for the first time a physically implemented resistive switching device was related to the originally proposed theory postulated in 1971, in which the memristor was described as the missing, fourth fundamental circuit element [2]. Despite the arising controversy following this claim [3], the application potential of memristive devices in technologies like in neuromorphic computation architectures [4][5][6], novel data storage [7], and memsensing [8,9] is unambiguous. Typically, memristors are two-terminal devices, which are capable of occupying different distinct resistive states, resulting from stimulation by an external electrical field.…”