Ultrahigh electron mobility in suspended graphene

TL;DR

This paper reports achieving ultrahigh electron mobility in suspended graphene, enabling better access to its intrinsic transport properties by reducing substrate effects and improving device cleanliness.

Contribution

The study demonstrates a method to suspend graphene and enhance its mobility beyond 200,000 cm^2/Vs, significantly improving its electrical transport characteristics.

Findings

Electron mobility exceeds 200,000 cm^2/Vs in suspended graphene.

Suspension reduces Dirac peak widths by a factor of 10.

In situ cleaning improves electrical transport.

Abstract

We have achieved mobilities in excess of 200,000 cm^2/Vs 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, non-suspended devices. This advance should allow for accessing the intrinsic transport properties of graphene.