title: Partially Fluorinated Graphene: Structural and Electrical Characterization.
abstract: Despite the number of existing studies that showcase the promising application of fluorinated graphene in nanoelectronics, the impact of the fluorine bonding nature on the relevant electrical behaviors of graphene devices, especially at low fluorine content, remains to be experimentally explored. Using CF4 as the fluorinating agent, we studied the gradual structural evolution of chemical vapor deposition graphene fluorinated by CF4 plasma at a working pressure of 700 mTorr using Raman and X-ray photoelectron spectroscopy (XPS). After 10 s of fluorination, our XPS analysis revealed a co-presence of covalently and ionically bonded fluorine components; the latter has been determined being a dominant contribution to the observation of two Dirac points in the relevant electrical measurement using graphene field effect transistor devices. Additionally, this ionic C-F component (ionic bonding characteristic charge sharing) is found to be present only at low fluorine content; continuous fluorination led to a complete transition to a covalently bonded C-F structure and a dramatic increase of graphene sheet resistance. Owing to the formation of these various C-F bonding components, our temperature-dependent Raman mapping studies show an inhomogeneous defluorination from annealing temperatures starting at ∼150 °C for low fluorine coverage, whereas fully fluorinated graphene is thermally stable up to ∼300 °C.
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Lanxia
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Srikar
authors.initials: S
authors.lastname: Jandhyala
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Greg
authors.initials: G
authors.lastname: Mordi
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Antonio T
authors.initials: AT
authors.lastname: Lucero
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Angelica
authors.initials: A
authors.lastname: Azcatl
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Rafik
authors.initials: R
authors.lastname: Addou
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Wallace
authors.affiliation: Texas Instruments , Dallas, Texas 75243, United States.
authors.forename: Luigi
authors.initials: L
authors.lastname: Colombo
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States.
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Kim
keywords: CVD graphene; GFETs; Raman; XPS; fluorinated graphene; ionic bond