Tuning graphene structures and electronic properties by Ion beam irradiation

Irradiation of ion-beam into graphene is interesting in view of defect-introduction and chemical modification of graphene. However, it is necessary to fabricate a sacrificial layer on graphene for decelerating ions and position them at the graphene surface due to high energy ion beam penetrating the substrate through graphene. In this study, we designed appropriate sacrificial layer and evaluated the effect of irradiation of air stable Au ion on the structure of graphene. The sacrificial layer thickness giving the least damage and the largest population of Au on graphene is determined by Monte Carlo simulation (SRIM2013). Au ion irradiation of 1×10¹⁵/cm^-2 were performed at 200 keV under 10⁻⁵ Pa by a tandem accelerator. Rutherford backscattering spectrometry revealed Au is successfully distributed near the surface of the substrate after irradiation in the case of photoresist sacrificial layer irradiated by Au ion. However, the resist layer becomes unremovable due to its change into amorphous carbon indicated by Raman spectra and XPS. The results using ZnO and NaCl as an alternative sacrificial layer will be also presented, where it has been confirmed that they could be removed by HCl and water respectively, even after Au ion irradiation.