Water-Mediated Ionic Migration in Memristive Nanowires with a Tunable Resistive Switching Mechanism

Abstract

Memristive devices based on electrochemical resistive switching effects have been proposed as promising candidates for in-memory computing and for the realization of artificial neural networks. Despite great efforts toward understanding the nanoionic processes underlying resistive switching phenomena, comprehension of the effect of competing redox processes on device functionalities from the materials perspective still represents a challenge. In this work, we experimentally and theoretically investigate the concurring reactions of silver and moisture and their impact on the electronic properties of a single-crystalline ZnO nanowire (NW). A decrease in electronic conductivity due to surface adsorption of moisture is observed, whereas, at the same time, water molecules reduce the energy barrier for Ag+ ion migration on the NW surface, facilitating the conductive filament formation. By controlling the relative humidity, the ratio of intrinsic electronic conductivity and surface ionic conductivity can be tuned to modulate the device performance. The results achieved on a single-crystalline memristive model system shed new light on the dual nature of the mechanism of how moisture affects resistive switching behavior in memristive devices.

Quantum Conductance in Memristive Devices: Fundamentals, Developments, and Applications

“…[ 146 ] Furthermore, for this kind of configuration, the electronic/ionic transport contributions in resistive switching can be easily regulated thanks to adsorbing chemical species (such as moisture) on the NW surface. [ 148 ] Thanks to the Schottky barriers of different height between the NW and the electrodes, such devices can exhibit a self‐limited current that prevents Joule heating and that can be easily modeled with two back‐to‐back diodes and a variable series resistance. [ 149 ] Finally, short‐term plasticity effects can be modeled starting from a potentiation‐depression rate balance equation, where coefficients are exponentially dependent upon applied voltage, as is typical of ionic transport.…”

Voltage-Controlled Conversion from CDS to MDS in an Azobenzene-Based Organic Memristor for Information Storage and Logic Operations

“…The device returns to the HRS after such a reset process. Therefore, the device can achieve a reversible transition between HRS and LRS due to the formation and disconnection of conductive filaments with the fast Set and Reset processes, which is useful for logic operation and information storage. , …”

“…Therefore, the device can achieve a reversible transition between HRS and LRS due to the formation and disconnection of conductive filaments with the fast Set and Reset processes, which is useful for logic operation and information storage. 54,55 The mechanism of the Ag/AZB:PMMA/FTO organic memristive device in this study can be described as follows. When a relatively low positive voltage (<1 V) is applied to the top electrode of the device (in the low voltage region), Ag + ions and electrons will move to the bottom and top electrodes, forming charged regions near their counter electrodes.…”

Structure‐Dependent Influence of Moisture on Resistive Switching Behavior of ZnO Thin Films

“…However, previous works revealed that moisture also has a strong impact on the Ag + ionic migration mechanism on ZnO crystalline surfaces. [ 49 ] Indeed, theoretical and experimental investigation revealed that water species adsorbed on a crystalline ZnO surface (here represented by grain surfaces) are responsible for a decrease of the diffusion barrier of Ag + ions, facilitating the formation of the metallic filament underlying resistive switching events. The lowering of the diffusion barrier was shown to be related to a qualitative change of the diffusion mechanism of silver ions that, in presence of moisture, move from one water molecule to the next one by forming AgOH complexes that prevent their interaction with Zn atoms on the surface.…”

“…The lowering of the diffusion barrier was shown to be related to a qualitative change of the diffusion mechanism of silver ions that, in presence of moisture, move from one water molecule to the next one by forming AgOH complexes that prevent their interaction with Zn atoms on the surface. [ 49 ]…”