Plasma treatments to improve metal contacts in graphene field effect transistor

Graphene formed via chemical vapor deposition was exposed to various plasmas (Ar, O-2, N-2, and H-2) in order to examine its effects on the bonding properties of graphene to metal. After exposing patterned graphene to Ar plasma, the subsequently deposited metal electrodes remained intact, enabling the successful fabrication of field effect transistor arrays. The effects of the enhanced adhesion between graphene and metals were more evident from the O-2 plasma than the Ar, N-2, and H-2 plasmas, suggesting that a chemical reaction of O radicals imparts hydrophilic properties to graphene more effectively than the chemical reaction of H and N radicals or the physical bombardment of Ar ions. The electrical measurements (drain current versus gate voltage) of the field effect transistors before and after Ar plasma exposure confirmed that the plasma treatment is quite effective in controlling the graphene to metal bonding accurately without the need for buffer layers. (C) 2011 American Institute of Physics. [doi:10.1063/1.3646506]