Electric Field-Dependent Evolution Dynamics of Conductive Filaments in 2D Material-Based Planar Memristors

2D materials have emerged as potential building blocks for electrochemical metallization (ECM) memristors with excellent performance. The evolution dynamics of conductive filaments (CFs) directly determine the resistance switching performance of the 2D material-based ECM memristors. However, achieving controllable CFs under the operation conditions remains challenging. Here, in situ transmission electron microscopy was employed to investigate the formation and evolution of CFs in Au/MoS2/Ag planar ECM memristors under electric fields, and various growth modes of CFs dependent on electric field strength were revealed. As the electric field intensity increased, the CFs exhibited diverse morphological variations, transitioning from a nanocluster-type to a continuous solid-type. Especially, the nanocluster-induced CF growth and nanobridge-assisted coalescence of nanoclusters under the electric field were observed, wherein bipolar electrochemical reactions were identified as playing a crucial role in the morphological evolution of nanoclusters and the formation of CFs. The results provide insights into the optimization of ECM planar memristors based on 2D materials.