Controlling the macroscopic electrical properties of reduced graphene oxide by nanoscale writing of electronic channels

The allure of all carbon electronics stems from the spread in physical properties, across all its allotropes. The scheme also harbours unique challenges, like tunability of band-gap,variability of doping and defect control. Here, we explore the technique of scanning probe tip induced nanoscale reduction of graphene oxide (GO), which nucleates conducting, sp^2 rich graphitic regions on the insulating GO background. Flexibility of direct writing is supplemented with control over degree of reduction and tunability of bandgap, through macroscopic control parameters. The fabricated reduced ––GO channels and ensuing devices are investigated via spectroscopic, and temperature and bias dependent electrical transport and correlated with spatially resolved electronic properties, using surface potentiometry. Presence of carrier localisation effects, induced by the phase-separated sp^2/sp^3 domains, and large local electric field fluctuations are reflected in the non-linear transport across the channels. Together the results indicate a complex transport phenomena which may be variously dominated by tunnelling, variable range hopping or activated depending on the electronic state of the material.