Defects Produced during Wet Transfer Affect the Electrical Properties of Graphene

Graphene has been widely used due to its excellent electrical, mechanical and chemical properties. Defects produced during its transfer process will seriously affect the performance of graphene devices. In this paper, single-layer graphene was transferred onto glass and silicon dioxide (SiO₂) substrates by wet transfer technology, and the square resistances thereof were tested. Due to the different binding forces of the transferred graphene surfaces, there may have been pollutants present. PMMA residues, graphene laminations and other defects that occurred in the wet transfer process were analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy. These defects influenced the square resistance of the produced graphene films, and of these defects, PMMA residue was the most influential; square resistance increased with increasing PMMA residue.