Study of supported CVD graphene irradiated by He and Au ions

In this work, a graphene monolayer deposited on the SiO2/Si substrate by means of Chemical Vapour Deposition (CVD) was irradiated using He and Au ions. The energy of used ions was 1.8 MeV and ion fluences varied in the range from 1.0 x 10(13) cm(-2) to 1.0 x 10(15) cm(-2). The different mass of Au and He ions leads to the significantly different electronic and nuclear stopping ratios and thus a difference in ion beam induced defects, of which the nature, size and density were estimated from the evolution of relative intensities of Raman lines. The chemical composition with possible oxidation of graphene layer and structural changes of the irradiated graphene were characterized by Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR). The surface conductivity was measured by using standard two point method. The used ion irradiation leads to defect production in graphene structures whose density increases with increasing ion fluence and is significantly more pronounced for heavier gold ions. The graphene modification causes the slight conductivity decrease in the case of He irradiation in accordance with the observed structural degradation and significant decrease of graphene conductivity after Au irradiation.