Researchers in School of Physical Sciences and Hefei National Laboratory for Physical Sciences at the Microscale in USTC designed an innovative method utilizing atomic force microscope tip to "write" nanoribbons directly on insulating graphene oxide (GO) under mild operating conditions. Their published results in the Nov.13 Nature Communications greatly raise the status of graphene in becoming one of the best materials for electronics.
Graphene is considered as a kind of optimistic two-dimensional material for constructing electronic circuits with its extraordinary high carrier mobility. Scientists have been focused on how to create well-defined nanoribbon out of highly conductive graphene. However, the researchers inWANG Xiaoping group and LUO Yi group in USTC went in a completely opposite way. They generated conductive nanostructure in insulating GO under arbitrary substrates, atmospheric pressure and low temperatures.
Experimental setup
They used a Pt-coated AFM tip to locally catalyze the reduction reaction of GO in hydrogen atmosphere. A shallow groove of only 80nm wide and 2μm long can be observed in topographical images and the resistance contrast is at least six orders of magnitude, much better than previous reported work. Also, the resistance of the structure, which follows simple Ohm Law, is found to depend on the length of the nanoribbons. This means the conductivity of reduction GO can be calculated and controlled through experimental manipulation. Further study of similar structure was also carried out by “writing” crossed nanoribbons and nanoribbon FET and both testified the significant character of high quality electronic equipment, with the estimated hole mobility to be about 21cm2V-1 S-1. Besides, Density Functional Theory calculation was employed to show the possible mechanism of the reduction process.
The topographical image of the crossed nanoribbons 
Three-dimensional current image obtained at 0.5V. (Color scale is 15nA) 
Schematic of the FET device 
(b): The topographical image of the reduced GO nanoribbon bridged between two electrodes (the white areas), the scale bar is200nm.
(c): The topographical and (d) the corresponding current images of the marked area in (b).
This state-of-art technology is mild, clean and straightforward compared to previous results and it provides a new idea to graphene-based nanoelectronics and sensing technologies.