A non-invasive approach to the resistive switching physical model of ultra-thin organic–inorganic dielectric-based ReRAMs

Abstract

The race to next-generation non-volatile memory is on, and ultra-thin (<5 nm) organic–inorganic hybrid dielectric-based ReRAMs are a top contender. However, their extremely small thickness hinders their processability through material characterization techniques, leaving gaps in our understanding of the resistive switching (RS) dynamics in the hybrid dielectric layer. Furthermore, the poor uniformity of key switching parameters remains a persistent issue in ReRAMs, which impedes any trends to be clearly defined through electrical characterization. This work uses electrical manipulation through a ramped-pulse series (RPS) method to improve the voltage and resistance fluctuations in the reset process of ultra-thin Al/Hf-hybrid/Ni devices. By analyzing their electrical behavior under different pulse and temperature conditions, we propose a comprehensive physical model that describes the operating mechanism of the device. Our results confirm the coexistence in the conductive filament (CF) of a hybrid metallic portion composed of Al and Hf₃Al₂ and an oxygen vacancy portion. The vacancies are found to play a significant role in RS, with most of them generated during the CF forming process and participating to different degrees in the filament rupture of the RPS-processed and non-RPS-processed devices via Joule heating, drift, and Fick forces. Additionally, we identify the cause of switching failure events to be based on the presence of an Al₂O₃ interlayer in the Al/Hf-hybrid interface.