Role of the Electrode Material on the RESET Limitation in Oxide ReRAM Devices

Abstract

Abstract Metal‐oxide‐based bipolar resistive switching (BRS) redox‐based resistive switching memory (ReRAM) shows many outstanding properties making it of interest as an emerging nonvolatile memory. However, it often suffers from a low R OFF / R ON ratio, while a large ratio is desired to compensate for read margin loss due to the intrinsic variability of the ReRAM cells. Understanding of the physical processes responsible for limitations of the R OFF and R ON in ReRAM cells is therefore of high importance. In this paper a study on the RESET process in BRS Ta 2 O 5 ‐based ReRAM cells is presented. The R OFF is found to be limited by a secondary volatile resistive switching mode that shows an opposite polarity compared to the main BRS mode. Based on results of switching kinetics measurements a physical model is proposed. It involves an oxygen exchange reaction at the metal‐oxide/active electrode interface combined with a drift‐diffusion induced migration of the resulting oxygen vacancy defects within the metal‐oxide. Incorporation of a thin oxygen‐blocking layer at the active interface allows for a suppression of the secondary switching mechanism. The improved RESET characteristic results in a strongly increased maximum R OFF . These results provide new insights into the role of the electrode material on the RESET process in BRS ReRAM cells.