Evolution between CRS and NRS behaviors in MnO2@TiO2 nanocomposite based memristor for multi-factors-regulated memory applications

Capacitive-coupled memristive effect provides a favorable way for developing novel multifunctional device since it simultaneously exhibits capacitive behavior and resistive switching (RS) effect. Herein, the memristive device with an Ag/MnO2@TiO2/FTO sandwich structure was fabricated, in which the MnO2@TiO2 nanocomposite with different thicknesses was deposited on F-doped SnO2 (FTO) substrates by hydrothermal method. It was observed that the device exhibits the evolution between capacitive-coupled RS (CRS) effect and negative differential resistance (NDR)-coupled RS (NRS) effect by tuning the MnO2 thickness and applied voltage. Through in-depth mechanistic analysis, it was inferred that the evolution behaviors are attributed to the interaction of ions and electrons in the MnO2@TiO2 nanocomposite. With the dielectric capacity of the functional layer increases, the migration of ions and electrons is hindered, which impairs the formation of conductive filaments (CFs), causing a large number of electrons/ions to collect on the interfaces of the functional layer/electrodes, resulting in an internal electric field, thereby observing a macroscopic capacitive effect. Therefore, this work provides a deep understanding of the evolution between CRS and NRS effects, opening a new way for building ultra-low-power multifunctional device for artificial intelligence applications.