  Resist residue from the device fabrication process is a general and
significant source of the metal/graphene contact interface contamination. In
this paper, Ultraviolet-Ozone (UVO) treatment is proven to be an effective way
of cleaning the metal/graphene interface. Electrical measurements of devices,
which were fabricated by using UVO treatment of the metal/graphene contact
region, show that stable and highly reproducible low contact resistance between
metal and graphene is obtained without affecting the electrical properties of
the graphene channel itself.
