Competition between Metallic and Vacancy Defect Conductive Filaments in a CH3NH3PbI3-Based Memory Device

Ion migration, which can be classified into cation migration and anion migration, is at the heart of redox-based resistive random access memory. However, the coexistence of these two types of ion migration and the resultant conductive filaments (CFs) have not been experimentally demonstrated in a single memory cell. Here we investigate the competition between metallic and vacancy defect CFs in a Ag/CH3NH3PbI3/Pt structure, where Ag and CH3NH3PbI3 serve as the top electrode and memory medium, respectively. When the medium layer thickness is hundreds of nanometers, the formation/diffusion of iodine vacancy (VI) CFs dominates the resistive switching behaviors. The V-I-based CFs provide a unique opportunity for the electrical-write and optical-erase operation in a memory cell. The Ag CFs emerge and coexist with VI ones as the medium layer thickness is reduced to similar to 90 nm. Our work not only enriches the mechanisms of the resistive switching but also would advance the multifunctionalization of resistive random access memory.