Near room temperature multilevel resistive switching memory with thin film ionic liquid crystals

Abstract

In this study, we demonstrate multilevel operation of nonvolatile resistive random-access memory (ReRAM) devices using thin films of an ionic liquid crystal (ILC), 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C₁₂mim][BF₄]), as a resistive switching layer. The present ILC-based ReRAM devices exhibit bipolar resistive switching behavior between the high resistance state (HRS) and the low resistance state (LRS) in the SmA phase of [C₁₂mim][BF₄] at near-room-temperature (30 °C) with an endurance of over 50 cycles and retention up to 2000 s. The observed resistive switching behavior of the device is caused by the formation and rupture of conductive filaments composed of trapped charges in the [C₁₂mim][BF₄] thin film, where the current conduction at the LRS follows the space charge limited current mechanism. Furthermore, multilevel resistive switching is achieved by controlling the voltage sweep rate and the reset voltage during the voltage sweep with stable endurance and reversibility. These findings indicate that ILC-based ReRAM devices have potential for application not only as next-generation information storage devices but also as neuromorphic devices owing to their multilevel resistive switching function.