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

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 n(D), a transition from ballistic to diffusive conduction occurs at n(D)similar or equal to 10(12) cm(-2) and the transport gap grows in proportion to root n(D). Considering the potential fluctuation related to the e-h puddle, the bandgap of graphene oxide is deduced to be Eg similar or equal to 30 root n(D)(10(12)cm(-2)) meV. The temperature dependence of conductivity showed metal-insulator transitions at n(D)similar or equal to 0.3x10(12) cm(-2), consistent with Ioffe-Regel criterion. For graphene oxides at n(D)>= 4.9x10(12) cm(-2), analysis indicated charge transport occurred via 2D variable range hopping conduction between localized sp(2) domain. Our work elucidates the transport mechanism at different extents of oxidation and supports the possibility of adjusting the bandgap with oxygen content.

Automated summary

Graphene oxides with different degrees of oxidation were prepared by controlling UV irradiation. The charge transport transitioned from ballistic to diffusive conduction with increasing oxygenous defect density, and the transport gap grew proportional to the square root of the defect density. The bandgap of graphene oxide was deduced to be dependent on the oxygen content. The study also revealed metal-insulator transitions and 2D variable range hopping conduction in the graphene oxide samples.