Damaging Graphene with Ozone Treatment: A Chemically Tunable MetalInsulator Transition

he discovery of graphene in early 20041,2 has sparked intense theoreti-cal and experimental activities, opening new prospects in carbon-based nanoelectronics.3,4 Indeed, pristine graphene exhibits genuinely large charge mobilities, and in the low density limit (close to the Dirac point), the measured conductivities are weakly temperature-dependent ranging typically within 215 e2/h. Conduction in a clean graphene monolayer deposited on an oxide sub-strate is limited by long-range scattering in-duced by charges trapped in the oxide, by mechanical deformations (ripples), or b