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 ∼2 ×10 ¹¹ cm ^-2 by suspending single layer graphene. Suspension ∼150 nm above a Si/SiO ₂ 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.