A nonvolatile memory device made of a graphene nanoribbon and a multiferroic BiFeO3 gate dielectric layer

We demonstrate a field-effect nonvolatile random access memory (NVRAM) device made of a graphene nanoribbon (GNR) and a multiferroic epitaxial BiFeO3 thin film. The GNR and the source/drain electrodes were formed by position-controlled dip-pen nanolithography. The NVRAM device exhibited asymmetric hysteresis behavior originating from the combination of the p-type semiconducting behavior of the GNR and the ferroelectric hysteresis of the BiFeO3 layer. The memory window of the NVRAM device was significantly improved by a NH3 annealing process which changed the p-type GNR to n-type.