One-step etching, doping, and adhesion-control process for graphene electrodes

Enhancing the electrical conductivity and reliability of graphene electrodes is critical for the practical realization of graphene-based electronics, since these factors influence the electrical performance of devices. To achieve such improvements in graphene electrodes requires additional processes such as doping and surface treatments, which inevitably complicate device fabrication. Here, we introduce a novel, straightforward one-step etching method, in which a catalytic copper substrate is etched in imidazole-containing ammonium persulfate solution, of simultaneously enhancing the electrical and adhesion properties of graphene grown on copper foil by chemical vapor deposition. Applying one-step etching method, the sheet resistance of monolayer graphene with 270 Ω/sq is obtained, while the adhesion of graphene is improved by 20%. Moreover, the electrical conductivity of graphene remained improved after storage for 30 days in ambient conditions without any passivation layers, and the graphene was almost transparent with transmittance of 97.7% at 550 nm. The enhancement of the electrical and adhesion properties of graphene originated from the synergistic adsorption of imidazole and etched Cu ions, which results in p-doping of graphene.