Ultrahigh electron mobility in suspended graphene

We have achieved mobilities in excess of 200,000 cm(2) V(-1)s(-1) at electron densities of similar to 2x10(11) cm(-2) by suspending single layer graphene. Suspension similar to 150 nin above a Si/SiO2 gate electrode and electrical contacts to the graphene was achieved by a combination of electron beam lithography and etching. The specimens were cleaned in situ by employing current-induced heating, directly resulting in a significant improvement of electrical transport. Concomitant with large mobility enhancement, the widths of the characteristic Dirac peaks are reduced by a factor of 10 compared to traditional, nonsuspended devices. This advance should allow for accessing the intrinsic transport properties of graphene. (C) 2008 Elsevier Ltd. All rights reserved.