Controlling the electrical transport properties of graphene by in situ metal deposition

The deposition effect of metals on graphene was studied by in situ field effect transistor (FET) measurements in high vacuum. Metals such as gold (Au), silver (Ag), and copper (Cu) were deposited onto clean graphene surfaces, followed by FET measurements. The results show that Ag and Cu cause a shift in the Fermi level in the graphene from the Dirac point into the conduction band while Au causes a shift into the valence band. The induced carrier concentration was estimated at 2-6 X 10(12)/cm(2). The shifts in the Fermi level of the graphene are explained by the different work functions of these metals. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3471396]