On‐Demand Reconfiguration of Nanomaterials: When Electronics Meets Ionics

Abstract

Rapid advances in the semiconductor industry, driven largely by device scaling, are now approaching fundamental physical limits and face severe power, performance, and cost constraints. Multifunctional materials and devices may lead to a paradigm shift toward new, intelligent, and efficient computing systems, and are being extensively studied. Herein examines how, by controlling the internal ion distribution in a solid‐state film, a material's chemical composition and physical properties can be reversibly reconfigured using an applied electric field, at room temperature and after device fabrication. Reconfigurability is observed in a wide range of materials, including commonly used dielectric films, and has led to the development of new device concepts such as resistive random‐access memory. Physical reconfigurability further allows memory and logic operations to be merged in the same device for efficient in‐memory computing and neuromorphic computing systems. By directly changing the chemical composition of the material, coupled electrical, optical, and magnetic effects can also be obtained. A survey of recent fundamental material and device studies that reveal the dynamic ionic processes is included, along with discussions on systematic modeling efforts, device and material challenges, and future research directions.

The future of electronics based on memristive systems

“…Fundamental device and materials characterizations have shown that the reconfiguration in memristors is typically driven by internal ion redistribution 3,5 . Specifically, the storage layer in a memristor is typically a few nanometres thick, thus even a moderate voltage drop across it can create a large enough electric field to drive the ionic processes to alter the ionic configuration of the material.…”

“…From the outside, the device looks like a resistor, and thus offers the potential for very-high-density integration and low-cost fabrication. However, unlike a static resistor, the storage layer can be dynamically reconfigured when stimulated by electrical inputs 2,3 . This material reconfiguration leads to memory effects, where changes in physical parameters, such as the device's resistance, can be used to store data and also directly process data.…”

“…Specifically, the storage layer in a memristor is typically a few nanometres thick, thus even a moderate voltage drop across it can create a large enough electric field to drive the ionic processes to alter the ionic configuration of the material. A typical process involves the oxidation, migration and reduction of cation or anion species in the storage layer, leading to changes of the local conductivity, normally in the form of the creation and annihilation of a conductive filament 3,5 . This process can be either abrupt (binary) or gradual (analogue), with different physical processes evolving at different timescales, leading to rich device behaviours in this seemingly simple device structure 12,13 .…”

Recent Advances in Memory Devices with Hybrid Materials

“…[69] The switching mechanism can involve filaments or interfaces. [4] In VCM, the conductive filament is formed by oxygen-vacancy defects in oxide-based solid electrolytes, and the anion diffusion occurs within the insulating layer. ECM, also known as conductive bridging random access memory (CBRAM), requires an electrochemically active metal electrode such as Ag or Cu.…”

Electrolyte Gated Oxide Pseudodiode for Inhibitory Synapse Applications

“…[1] Conventionally, neuromorphic engineering is based on von Neumann architecture where the processor and the memory are physically separated. Recently, solid state electronic devices were designed for neuromorphic device applications, including memristors, [3,4] new-conceptual transistors, [5,6] spin-orbit torque devices, [7] spintronic oscillators, [8] etc. In nervous system, a synapse connects two neurons, underlining signal transmitting and information processing function.…”