Nonvolatile unipolar resistive switching in ultrathin films of graphene and carbon nanotubes

We report unipolar resistive switching in ultrathin films of chemically produced graphene (reduced graphene oxide) and multiwalled carbon nanotubes. The two-terminal devices with yield >99% are made at room temperature by forming continuous films of graphene of thickness ∼20 nm on indium tin oxide coated glass electrode, followed by metal (Au or Al) deposition on the film. These memory devices are nonvolatile, rewritable with ON/OFF ratios up to ∼ 105 and switching times up to 10 μs. The devices made of MWNT films are rewritable with ON/OFF ratios up to ∼400. The resistive switching mechanism is proposed to be nanogap formation and filamentary conduction paths.

► We demonstrate unipolar resistive switching in ultrathin films of reduced graphene oxide and carbon nanotubes.
► The ON–OFF ratio in graphene devices varies from ∼ 106 to 102 depending on pulse widths of the applied voltage pulses.
► The ON–OFF ratio for nanotube devices is ∼40.
► The switching mechanism is proposed in terms of nanogap formation.