Effects of Fluorine Termination of Carbon Nanowall Edges on Their Electrical Properties by Ar/NO/F$_{2}$ Mixture Gas Treatments

Carbon nanowalls (CNWs) are one of graphene materials. They consist of multiple graphene sheets grown vertically on the substrate and form a maze-like wall structures. Therefore, a chemical termination of high-density graphene edges on the top regions is essential to control their unique properties. In this study, irradiation effects of fluorine (F) atoms generated using Ar/NO/F$_{2}$ gas mixture on changes in chemical bonding structure, crystallinity, and electrical properties of the CNWs, fabricated by a radical injection-plasma enhanced CVD (RI-PECVD) system, were investigated. In the Raman spectra, decrease in relative intensity of D-band peak was found after the Ar/NO/F$_{2}$ treatment, which indicates crystallinity improvement of CNWs. According to XPS, F incorporation into the CNWs and formation of related C-F bonds obviously occurred. As the exposure temperature increased, both the F contents in the CNWs and crystallinity improvements were enhanced. Furthermore, the higher electrical conductivities were obtained after the Ar/NO/F$_{2}$ gas treatment at a higher temperature. We demonstrated that the electrical properties could be controlled by the F termination of the graphene edges without degradation of the crystallinity.