Multilevel Resistive Switching Dynamics by Controlling Phase and Self‐Assembled Nanochannels in HfO₂

Abstract

A resistive switching device with precise control over the formation of conductive filaments (CF) holds immense potential for high‐density memory arrays and atomic‐scale in‐memory computing architectures. While ion migration and electrochemical switching mechanisms are well understood, controlling the evolution of CF remains challenging for practical resistive random‐access memory (RRAM) deployment. This study introduces a systematic approach to modulate oxygen vacancies (OV) in HfO2 films of Ag/HfO2/Pt‐based RRAM devices by controlling the substrate temperature. At 300 °C, the HfO2 film exhibits a dominant monoclinic phase with maximum OV concentration, which plays a key role in achieving optimal multilevel resistive switching behavior. Self‐assembled nanochannels in the HfO2 films guide CF evolution, and the diffusion of Ag at inside these films suggests a synergistic interplay between OV and Ag⁺ ion migration for reseting the voltage‐controlled resistive states. This approach addresses the endurance/retention trade‐off with an impressive Ron/Roff ratio of ≈8000 while demonstrating growth temperature‐driven OV modulation as a tool for multi‐bit data storage. These findings provide a blueprint for developing high‐performance oxide‐based RRAM devices and offer valuable insights into multilevel resistive switching mechanisms, paving the way for future low‐power, high‐density memory technologies.