The density of states of graphene underneath a metal electrode and its correlation with the contact resistivity

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.