(color online) Graphene-oxide-doped RRAM.^[49] (a) The switching characteristics of Zr:SiO_x film (blue curve) and Zr:SiO_x/C:SiO_x film (red curve), respectively. (b) Raman spectra of C sp2 and C sp3 in C:SiO_x film, which confirms the existence of graphene oxide. (c) Schematic of graphene-oxide-doped RRAM mechanism.