Characterization of graphene-on-insulator films formed using plasma based surface chemistry

This research explores the surface chemistry of halogen based plasmas on silicon carbide and is aimed at the synthesis of large area graphene-on-insulator films. In these studies, 6H-SiC (0001) substrates were etched using either CF4 and Cl2 based plasmas and then thermally annealed. The resulting surfaces were analyzed using x-ray photoelectron spectroscopy, reflection high energy electron diffraction, atomic force microscopy, and Raman spectroscopy. The analyses showed that the etching process selectively etched silicon to produce carbon rich surface layers on the silicon carbide substrate, and when annealed, these carbon rich layers formed graphene films with halogen- and oxygen-based defects. The thickness of the graphene was controlled by the plasma etch parameters. Two point current-voltage measurements were used to characterize the electrical properties of the films. The current-voltage plots exhibited back-to-back Schottky behavior which suggests that the defects open a band gap in these films. Current-voltage data were used to determine the Schottky barrier height, carrier density, and the upper limit for the film resistivity.