Patterning the graphene surface is a significant topic in the future graphene applications, since a number of functionalities of graphene were enabled by surface chemical modification; the two-dimensional structure of graphene offers an unique way to engineer the carriers by using surface modification.
A group from Northwestern University, lead by Mark Hersam, had demonstrated the sub-5-nm nanofabrication can be realized by using the scanning tunneling microscopy.
A layer of PTCDA was served as a chemical resist which can be desorbed from the surface of graphene by controlling the bias voltage or the tunneling current. The PTCDA was firstly deposited onto graphene surface by thermal evaporation, and the PTCDI-C8 layer was formed following the PTCDA deposition. The outcome shows that the PTCDI-C8 prefer to stay in the remaining graphene area where lack of the PTCDA layer. Moreover, they employed the feedback-controlled lithography (FCL) to eliminate the ununiformity of desorption, thus they are able to define the clear pattern on PTCDA layer and fill up the desorbed area with PTCDI-C8. This work has revealed the possibilities of nanofarication, which could be used for the selective area functionalization or etching process in the future nanoelectronic devices. I think this technique is also good for the study of surface modified-graphene.
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