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 VI-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 ∼90 nm. Our work not only enriches the mechanisms of the resistive switching but also would advance the multifunctionalization of resistive random access memory.