Nanoscale capacitive behaviour of ion irradiated graphene on silicon oxide substrate

Single layers of graphene obtained by mechanicla exfoliation of highly oriented pyrolytic graphite and deposited on a SiO2/n Si substrate were irradiated with high energy (500 keV) C ions Controlled amounts of defects were introduced in graphene by a precise control of the ion fluence ranging grom 1 x 10(13) to 1 x 10(14) cm(-2). Scanning capacitance spectroscopy (SCS) was used as non-destructive characterization technique to probe the effect of irradiation defects on the electrical properties of graphene. A wider variation between the capacitance curves measured at different positions on irradiated graphene is found in comparison with the pristine graphene. The quantum capacitance per unit area C-q' was extracted from raw data. In particular an increase of C-q' is associated to the damaged regions.