  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, sp2 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 localization effects, induced by the phase-separated sp2/sp3
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.
