Scanning Electrochemical Microscopy as a Characterization Tool for Reduced Graphene Oxide Field Effect Transistors

Abstract

Reduced graphene oxide coated SiO2/Si substrates were obtained by wet-chemical reduction of graphene oxide for the use as semiconductor material in field-effect transistors. The morphological and chemical characterization was done by using SEM, Raman spectroscopy and XPS. Raman and XPS measurements can characterize the success of the graphene-oxide reduction, but only for small parts spots of the surface (e.g. 0.41 µm 2 laser spot size with Raman). In order to evaluate larger surface areas and the electrochemical activity of the graphene oxide and reduced graphene oxide, additional spectroscopic measurements using the SECM were performed. The samples coated with unreduced graphene oxide showed no electrochemical activity, while reduced graphene oxide samples showed conducting properties. Further information about the topology of the surface was obtained by applying the SECM constant distance mode. The degree of graphene coverage was calculated from SECM data and compared to the coverage obtained by SEM. It was found that 68±7% coverage is sufficient to ensure electronic contact between the Source and Drain electrodes (resistance less than 1 kΩ). Functionality of the fabricated field effect transistors was demonstrated by titration of pH solutions and characterization of the characteristic curves.

Scanning Probe Microscopy for Nanoscale Electrochemical Imaging

“…Schuhmann and co-workers reported shear-force feedback SECM (SF-SECM) . A reduced graphene oxide-field emission transistor (rGO-FET) device was characterized by SF-SECM . We reported living cell topography and electrochemical imaging by SF-SECM. , The topographies and the electrochemical activities of a blank SiO 2 /Si substrate, a GO substrate, and a rGO substrate were also investigated.…”

Reduced Graphene Oxide as a Monolithic Multifunctional Conductive Binder for Activated Carbon Supercapacitors

“…The inset shows the c-AFM measurement geometry. We note here however that c-AFM probes the electrodes in a dry state and not under electrochemical conditions 44 and can thus only assess the electrodes’ conductivity in a semiquantitative manner, but it cannot elucidate the electrochemical transfer resistances and transport mechanisms relevant for a working supercapacitor device.…”