Spatially resolved chemical analysis of photodecomposition and doping effect of fluoropolymer-covered graphene

Abstract

We have studied the photo-decomposition of fluoropolymer-covered graphene and its effects on the electrical properties of embedded graphene using spatially resolved X-ray photoemission spectroscopy. From the comparative approach to the photo-decomposition and chemical analysis, we clearly prove that the fluorine atoms are desorbed from the sample surface by photon irradiation, resulting in a change of difluoride into a monofluoride form. As this photo-induced chemical modification proceeds, the dipole field changes strongly, which is responsible for the field-driven Dirac point realignment of the graphene layer. The desorption temperature of the photo-modified fluoropolymer was similar to that without photon irradiation (286 °C; ∼0.047 eV); this similarity means that photo-modification did not cause chemical interactions between the fluoropolymer and graphene.