Graphene oxide decorated with oxygen functional groups is a promising candidate as an active layer in resistive switching devices due to its controllable physical-chemical properties, high flexibility, and transparency. However, the origin of conductive channels and their growth dynamics remain a major challenge. We use in situ transmission electron microscopy techniques to demonstrate that nanoscale graphene oxide sheets bonded with oxygen dynamically change their physical and chemical structures upon an applied electric field. Artificially engineered bilayer reduced graphene oxide films with asymmetric oxygen content exhibit nonvolatile write-once-read-many memory behaviors without experiencing the bubble destruction due to the efficient migration of oxygen ions. We clearly observe that a conductive graphitic channel with a conical shape evolves from the upper oxygen-rich region to the lower oxygen-poor region. These findings provide fundamental guidance for understanding the oxygen motions of oxygen-containing carbon materials for future carbon-based nanoelectronics.
Keywords: bilayer structure; conductive filament; graphene oxide; in situ TEM; resistive switching.