Resistive random access memory (RRAM) is considered as a promising candidate for the next-generation nonvolatile memories (NVM) due to its high storage density, reduced power consumption, and fast switching speed. Transition metal oxides are widely utilized to RRAM as insulator, which exhibit stable structure, high endurance and retention, and shrinking ability under several nanometers.

In order to realize higher endurance and stability while reducing the size, knowing the mechanism of filaments formation and the interaction between adjacent nanodevices are essential. In this work, three-dimensional vertical RRAM (VRRAM) array architectures were built to access and organize data, which are expected to high density application potential. In our simple MIM structure, ZnO is the insulator, and Ag and Pt are served as active electrode and inert electrode, respectively. Each electrodes intersection contains two types of RRAM devices (Ag/ZnO/Pt, Pt/ZnO/Pt). By utilizing in-situ transmission electron microscope (TEM), we could observe the dynamic switching behaviors of two neighboring devices and realize the interaction between them. While the devices sizes scale down to few nanometers scale, the evolution of different types of filaments provides important information to improve the stability and performance of the devices.