Now researchers have a new focus to pursue the band gap opening of graphene.
BN thin film, a two dimensional insulator, has a band gap > 5 eV and very similar structure to graphene. Some theoretical calculations have suggested the hybrid-BNC film and graphene on BN could be the potential way toward band gap engineering.
Besides, the BN layer can also be grown on copper by CVD synthesis, just like the graphene. I believe that the BN film and graphene should have some interesting interactions between them. For example, Philip Kim's group used BN as the substrate for making high mobility graphene devices, since the BN is an atomically smooth and dangling-bond-free insulator, which makes it an ideal dielectric substrate. However, the problem is still there, the creation of the band gap is usually accompanied with a decrease of carrier mobility.
It seems still a long way to go for making the effective graphene transistors.
Here are some of the recent works in BN research
http://www.nature.com/nmat/journal/v9/n5/full/nmat2711.html
http://www.nature.com/nnano/journal/v5/n10/full/nnano.2010.172.html
http://pubs.acs.org/doi/abs/10.1021/nl1022139
http://pubs.acs.org/doi/abs/10.1021/nl1023707
http://onlinelibrary.wiley.com/doi/10.1002/smll.201001628/abstract
http://pubs.acs.org/doi/abs/10.1021/jp110985w
Nanofabrication of graphene
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.
