Charge transport in CVD graphene

Marishka Oquendo Mustafa, Gabriel Calderon, Josee Vedrine, Gang Hee, Allen Johnson, Nicholas Pinto

Abstract


Graphene is a mono-layer of sp2 bonded carbon atoms arranged in a honeycomb pattern. It is considered a promising candidate for the next generation of electronic materials as it exhibits both electron and hole conduction with extremely high carrier mobilities. Graphene films were prepared via chemical vapor deposition and then transferred to doped Si/SiO2 wafers. It was washed in toluene several times to remove any organic deposits left behind during the transfer process. Atomic force microscopy images shows that the graphene surface is very rough. The graphene device was then electrically characterized in a field effect transistor configuration as a function of temperature and the resistance calculated at the Dirac point minimum of the device transconductance curve. The Dirac point resistance showed weak temperature dependence characteristic of graphene. Thermally evaporating 1nm of silver (Ag) over the device reduced the surface roughness and made the graphene surface more planar. Electrically characterizing the device again showed that there was reduced mobility but no change in the charge transport mechanism. Our results imply that the charge mobility in graphene is largely governed by the contact with the substrate and the charge transport mechanism is unaffected after covering the surface with 1nm of silver.


Keywords


Graphene; Mobility; Temperature

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