Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation.

Abstract

Graphene oxides with different degrees of oxidation are prepared by controlling UV irradiation on graphene, and the charge transport and the evolution of the transport gap are investigated according to the extent of oxidation. With increasing oxygenous defect density , a transition from ballistic to diffusive conduction occurs at cm and the transport gap grows in proportion to . Considering the potential fluctuation related to the puddle, the bandgap of graphene oxide is deduced to be meV. The temperature dependence of conductivity showed metal–insulator transitions at cm, consistent with Ioffe–Regel criterion. For graphene oxides at cm, analysis indicated charge transport occurred via 2D variable range hopping conduction between localized domain. Our work elucidates the transport mechanism at different extents of oxidation and supports the possibility of adjusting the bandgap with oxygen content.