  The density of states (DOS) of graphene underneath a metal is estimated
through a quantum capacitance measurement of the metal/graphene/SiO2/n+-Si
contact structure fabricated by a resist-free metal deposition process.
Graphene underneath Au maintains a linear DOS - energy relationship except near
the Dirac point, whereas the DOS of graphene underneath Ni is broken and
largely enhanced around the Dirac point, resulting in only a slight modulation
of the Fermi energy. Moreover, the DOS of graphene in the contact structure is
correlated with the contact resistivity measured using devices fabricated by
the resist-free process.
