A while back, DARPA created a program called CERA (Carbon electronics for RF applications) and funded two groups - one led by IBM and the other HRL. The aim is to use graphene for RF applications, and to grow graphene on large area substrates for use in integrated RF circuits. Now we are beginning to see initial results from research efforts.
In IEDM 2008, IBM reported the fabrication of RF transistors using flaked graphene. Around the same time, HRL too reported RF transistors - but using graphene grown on SiC. Ofcourse the HRL group’s fT was much lower than that of IBM since grown graphene is not yet as pristine as cleaved graphene. In their latest paper in Electron Device Letters (May), the HRL group reports results of RF transistors on 2″ 6H-SiC substrates. The fT is reported to be around 5 GHz.