Effects of the Molecular Chain Length of Polyimide on the Characteristics of Organic Resistive Random Access Memories

We developed organic resistive random access memory (ReRAM) devices using spin-coated polyimide (PI) as the resistive layer. In this article, the effect of the chain length of the PI macromolecules on the electrical performance of ReRAM devices was studied. The chain length of the PI macromolecule was controlled by repeating the addition step of 4, 4'-diaminodioxydianiline in a polyamic acid precursor. A long molecular chain of the PI film could be obtained by increasing the addition times. The electrical properties of the PI-based ReRAM devices revealed that the leakage current in the high-resistance state and memory window can be improved by increasing the molecular chain length of the PI film. A model is proposed to explain the effects of the chain length on the conduction mechanism in the PI film. Moreover, PI films with long molecular chains exhibited an increased retention time.