Highly improved performance in Zr0.5Hf0.5O2 films inserted with graphene oxide quantum dots layer for resistive switching non-volatile memory

Abstract

Resistive memory (RRAM) based on a solid–electrolyte insulator is a type of critical nanoscale device with promising potential in non-volatile memory, analog circuits and neuromorphic synapse applications. However, the random nature of the nucleation and growth of the conductive filaments (CFs) causes instability of the switching parameter, which is a major obstacle for RRAM performance improvement. Herein, we report a novel approach to resolve this challenge by inserting graphene oxide quantum dots (GOQDs) in Zr_0.5Hf_0.5O₂ (ZHO) films. The Ag/ZHO/GOQDs/ZHO/Pt stacked device exhibited a reversible bipolar resistive switching (RS) behavior under a direct current (DC) sweeping voltage. The device with GOQDs exhibited better performance than the device without GOQDs with characteristics such as reduced threshold voltage, uniform distribution of set and reset voltage, robust retention, fast switching speed and low switching power. The underlying RS mechanism of RRAM was ascribed to the formation and rupture of the nanoscale CFs inside the solid–electrolyte oxide layer. The GOQDs could guide the CF nucleation and growth direction to provide a superior uniformity of RS properties and shorten the effective distance of Ag⁺ motion through enhancing the local electric field on the GOQD sites. The overall device performance of the GOQDs-inserted memristor has the potential to open up a new route to improve the reliability of oxide-based RRAM, which could significantly accelerate their existing applications.