Understanding the Electrical Characteristics of Electrochemical Metallization Memristors through Identification of Conduction Channel in Entire Active Area

Physical observation of electrochemical metallization (ECM) channel is required for understanding the electrical characteristics of ECM memristors. Although numerous studies have explored to identify the ECM channels, the majority of approaches have been limited to in-situ systems and localized areas, lacking a comprehensive demonstration of their findings. This study focuses on interpreting the different electrical characteristics of ECM memristors through identification of ECM channels using a new method inspired by etch pit detection on Si surface for determining copper contamination. Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) were utilized to detect and analyze conductive channels within the switching medium after real operation. Interestingly, devices with insulating amorphous carbon (a-C) as medium layer exhibited multiple channels, while devices with semiconducting a-C layers showed a single channel in the on-state. Furthermore, devices with a single channel demonstrated more uniform switching parameters, including high resistance state and set voltage, compared to devices with multiple channels. However, devices with multiple channels exhibited better retention properties .In addition, intermetallic conductive channels were confirmed, resulting from the mixing of Cu active metal ions with the Pt bottom electrode in high current density conditions. The findings of this work provide valuable insights into interpreting ECM memristor performance based on the formation of channels and inspire device design strategies for improving device performance.

Graphical Abstract