Photoelectron spectroscopy studies of plasma-fluorinated epitaxial graphene

Abstract

Fluorination of graphene has emerged as an attractive approach toward manipulating its physical, chemical, and electronic properties. To this end, we have demonstrated the viability of sulfur hexafluoride plasmas to fluorinate graphene as a safer alternative to the commonly reported techniques of fluorination that include exposures to fluorine and xenon difluoride gas. Incorporation of fluorine moieties on graphene after SF 6 plasma-treatment was confirmed by x-ray photoelectron spectroscopy. Modifications in the valence band states of graphene after plasmatreatment were characterized by ultraviolet photoelectron spectroscopy. Increase in work function of plasma-treated graphene demonstrates the ability of plasma-assisted fluorination to modify the electron emission characteristics of graphene. Raman spectroscopy reveals that the majority of carbon atoms in graphene retain their sp 2 hybridization after the plasma-treatment.

Growth and characterization of ultrathin carbon films on electrodeposited Cu and Ni

“…The work function of 4.3‐4.4 eV was calculated from the cut‐off of these spectra (see the inset in Figure ). It should be noted, that the literature data for work function of graphite and graphene are very similar; therefore, it is not possible to identify the presence of graphene only from these measurements. More information on the VB of the films was obtained from the He II spectra reported in Figure A.…”

Effect of titanium nitride coating on physical properties of three-dimensional graphene

“…13b, a shoulder at about 2.25 eV can be seen for both samples. This shoulder is ascribed to the emitted photoelectrons from the 2p-state of graphene [48]. The presence of these peaks in the UPS spectrum of TiN/3DG declares that the sp 2 hybridized carbon skeleton of graphene has been retained after applying TiN coating.…”

Plasma Treatment of Graphene Oxide

“…After heat treatment at T = 500 Ci na nA r atmosphere with a duration of 10 min, the fluorine is completely removed, the intensities of D and D 0 peaks, as well as the I D /I G ratio drastically decrease [55]. In [56] the effect of pure SF 6 plasma generated in an reactive ion etcher (RIE) system at a radio-frequency of 13.56 MHz on epitaxial grapheme. An rf power of 50 W and an SF 6 partial pressure of 100 mTorr were used for all experiments.…”

“…The study of the fluorination of various carbon materials by plasma makes it possible to understand more fully the effect of such treatment on the properties of graphene oxide. The effect of plasma SF 6 fluorination on the properties of graphene was investigated in [55][56][57][58][59]. Baraket et al the chemical vapor deposition (CVD) graphene was treated with a pulsed Ar/SF 6 plasma (pulse duration 2 ms and period 20 ms, plasma exposure time was 6 s and the total treatment time was 60 s) at a pressure of 50 mTorr, where the reactive gas was 5% of the total flow rate [55].…”