Anderson localization of graphene by helium ion irradiation

Irradiation of a single-layer graphene (SLG) with accelerated helium ions (He⁺) controllably generates defect distributions, which create a charge carrier scattering source within the SLG. We report direct experimental observation of metal-insulator transition in SLG on SiO₂/Si substrates induced by Anderson localization. This transition was investigated using scanning capacitance microscopy by monitoring the He⁺ dose conditions on the SLG. The experimental data show that a defect density of more than ∼1.2% induced Anderson localization. We also investigated the localization length by determining patterned placement of the defects and estimated the length to be several dozen nanometers. These findings provide valuable insight for patterning and designing graphene-based nanostructures using helium ion microscopy.