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

TL;DR

This study measures the density of states of graphene beneath different metals and correlates it with contact resistivity, revealing metal-specific electronic modifications relevant for device performance.

Contribution

It provides the first direct measurement of the DOS of graphene under metal contacts and links these electronic properties to contact resistivity.

Findings

Graphene under Au retains a linear DOS-energy relationship.

Graphene under Ni shows a broken and enhanced DOS near the Dirac point.

DOS variations are correlated with differences in contact resistivity.

Abstract

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.