Noncontact Tunneling in Methylammonium Lead Iodide (CH₃NH₃PbI₃): Evidence of Bipolar Resistive Switching through Defect Migration

We present resistive switching characteristics of methylammonium lead iodide (CH₃NH₃PbI₃) films through a noncontact electrical poling process toward memristive applications. The noncontact nature of the poling process was induced with a scanning tunneling microscope tip, so that the formation of metal filaments could be ruled out. The perovskite films were seen to exhibit resistive switching upon application of a voltage pulse in the presence of a high-resistive state and a low-resistive state; the magnitude and the width of the voltage pulse were varied to deliberate on the parameters necessary to activate the switching phenomenon. Among the underlying mechanisms proposed so far, the formation and the subsequent rupture of metal-like filaments because of the migration of iodide vacancies have been identified to be responsible for resistive switching in the perovskite material.