Effect of the polarity of carbon-fluorine bonds on the work function of plasma-fluorinated epitaxial graphene

Abstract

Work function engineering of graphene facilitates its application as a transparent electrode material in organic electronic devices. Toward this end, we demonstrate the dependence of the work function of plasma-fluorinated epitaxial graphene on the polarity of carbon-fluorine bonds which is controlled by the nature of chemical bonding (ionic, semi-ionic, or covalent) between fluorine and carbon atoms. The work function of fluorinated graphene was measured using ultraviolet photoelectron spectroscopy and the polarity of carbon-fluorine bonds was established using x-ray photoelectron spectroscopy.

Electric-Carrying Nanofriction Properties of Atomic-Scale Steps on Graphene

“…be defined as the minimal energy that brings an electron from the main region of a crystal to the outside. It is closely related to dipole moment at the surface of a crystal [32,33]. So, changes in the work function of graphene surface were caused by the oxygenated functional groups.…”

Chemistry, properties, and applications of fluorographene

“…According to this technique, generated fluorine radicals adsorb onto carbon lattice and create different C-F bonds. The fluorine-based compounds CF 4 [53] , [54] , [55] , [56] , SF 6 [57] , [58] , [59] , [60] , [61] , and F 2 [62] represent the most common plasma sources. Photochemical fluorination is an innovative and ecofriendly method for the production of fluorinated graphene.…”

Local work function measurements of plasma-fluorinated epitaxial graphene

“…1(a)] which is in agreement with our previous report. 2 Thus, the originally n-doped EG becomes p-doped as expected from the surface dipole induced by carbon-fluorine bond polarity. AFM and SKPM scans were performed over the same region as shown in Figs.…”

“…Local work function measurements of plasma-fluorinated epitaxial graphene Sonam D. Sherpa, 1 Jan Kunc, 2 Yike Hu, 2 Galit Levitin, 1 Walt A. de Heer, 2 Claire Berger, 2,3 and Dennis W. Hess 1,a) 1 School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA Plasma-fluorination is an attractive route toward the work function engineering of graphene. The effect of surface topography of epitaxial graphene grown on silicon carbide on the increase in work function after plasma-fluorination was investigated using scanning Kelvin probe microscopy.…”

“…1 Our studies have also established the correlation between the work function of fluorinated EG and the polarity of carbon-fluorine bonds. 2 However, factors that determine the polarity of carbon-fluorine bonds in fluorinated EG are not apparent. Previously reported studies on graphite have suggested that a lower concentration of fluorine results in ionic bonding between carbon and fluorine atoms while bonding becomes more covalent as the fluorine concentration increases.…”