Three-Dimensional Reconstruction of Conductive Filaments in HfOx-Based Memristor

HfOx-based memristor has been studied extensively as one of the most promising memories for the excellent nonvolatile data storage and computing-in-memory capabilities. However, the resistive switching mechanism, relying on the formation and rupture of conductive filaments (CFs) during device operations, is still under debate. In this work, the CFs with different morphologies after different operations-forming, set, and reset-are clearly revealed for the first time by 3D reconstruction of conductive atomic force microscopy (c-AFM) images. Intriguingly, multiple CFs are successfully observed in HfOx-based memristor devices with three different resistive states. CFs after forming, set, and reset exhibit the typical morphologies of hourglass, inverted-cone, and short-cone, respectively. The rupture location of CFs after the reset operation is also observed clearly. These findings reveal the microscopic behaviors underlying the resistive switching, which could pave the road to design and optimize oxide-based memristors for both memory and computing applications.

Automated summary

In this study, the conductive filaments (CFs) with different morphologies after forming, set, and reset operations in HfOx-based memristor devices are clearly revealed for the first time through 3D reconstruction of conductive atomic force microscopy (c-AFM) images. Multiple CFs are successfully observed in devices with three different resistive states, exhibiting hourglass, inverted-cone, and short-cone morphologies. The rupture location of CFs after the reset operation is also clearly observed. These findings provide insights into the resistive switching mechanism and can contribute to the design and optimization of oxide-based memristors for memory and computing applications.