Fabrication and characterization of networked graphene devices based on ultralarge single-layer graphene sheets

Ultralarge-scale single-layer graphene (SLG) sheets are obtained by chemically reduction process in aqueous media. The resulting SLG sheets are investigated by atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopic. Based on the ultralarge SLG sheets, the graphene FETs are fabricated using SLG sheets and networked graphene (NW) sheets, respectively. The electrical characterizations indicate that the NW devices exhibit higher carrier mobility as compared to SLG devices. Moreover, the subsequent thermal annealing process further improves the effective hole mobility to 0.55 cm^-2 /Vs. This study demonstrates a simple way to obtain graphene transistors with high mobility, which provides a promising application in printable graphene-based nanoelectronics.