Fluorination of edges and central areas of monolayer graphene by SF6 and CHF3 plasma treatments.

In this work, we report the fluorination of edges and central areas of monolayer graphene by SF6 and CHF3 plasma treatments. After fluorination by SF6 plasma, G and 2D peaks of Raman spectroscopy for the edges have upshifts, which are much bigger than the upshifts for central areas of monolayer graphene. For the intensity ratio of I(2D)/I(G), it becomes smaller after SF6 plasma treatments and magnitude of change is similar for the edges and that of the central areas. These observations indicate that the fluorination by SF6 plasma treatments can induce p-doping to graphene, which is more significant for the edges comparing to the central areas. Moreover, the ratio of I(D)/I(G) becomes larger both for the edges and the central areas. For CHF3 plasma treatments, although similar results can be obtained, the p-doping to graphene is less and more defects are introduced comparing to SF6 plasma treatment. Therefore, for fluorination of monolayer graphene, SF6 plasma is better than CHF3 plasma.