title: Layer-dependent fluorination and doping of graphene via plasma treatment.
abstract: In this work, the fluorination of n-layer graphene is systematically investigated using CHF₃ and CF₄ plasma treatments. The G and 2D Raman peaks of graphene show upshifts after each of the two kinds of plasma treatment, indicating p-doping to the graphene. Meanwhile, D, D' and D + G peaks can be clearly observed for monolayer graphene, whereas these peaks are weaker for thicker n-layer graphene (n ≥ 2) at the same experimental conditions. The upshifts of the G and 2D peaks and the ratio of I(2D)/I(G) for CF₄ plasma treated graphene are larger than those of CHF₃ plasma treated graphene. The ratio of I(D)/I(G) of the Raman spectra is notably small in CF₄ plasma treated graphene. These facts indicate that CF₄ plasma treatment introduces more p-doping and fewer defects for graphene. Moreover, the fluorination of monolayer graphene by CF₄ plasma treatment is reversible through thermal annealing while that by CHF₃ plasma treatment is irreversible. These studies explore the information on the surface properties of graphene and provide an optimal method of fluorinating graphene through plasma techniques.
authors.affiliation: National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China.
authors.forename: Minjiang
authors.initials: M
authors.lastname: Chen
authors.forename: Haiqing
authors.initials: H
authors.lastname: Zhou
authors.forename: Caiyu
authors.initials: C
authors.lastname: Qiu
authors.forename: Huaichao
authors.initials: H
authors.lastname: Yang
authors.forename: Fang
authors.initials: F
authors.lastname: Yu
authors.forename: Lianfeng
authors.initials: L
authors.lastname: Sun