First principles study of the voltage-dependent conductance properties of n-type and p-type graphene–metal contacts

• Transmission spectra of n-type and p-type graphene–metal contacts are obtained.
• Voltage-dependent resistances of contacts are also calculated and interpreted.
• Asymmetric conductance of graphene–metal contacts is verified.
• n-Type and p-type doping of graphene is observed through the asymmetric resistance.
• It is shown that a polynomial model can represent current–voltage characteristics.

Investigation of the conductance properties of metal–graphene contacts is essential for the future nanoelectronics technology. In this study, we focus on the conductance mechanism and the voltage-dependent transport properties of both p-type and n-type graphene–metal contacts. Copper and gold are chosen as the contact metal for n-type and p-type doped graphene–metal interface, respectively. Utilizing first principles quantum mechanical calculations with density functional theory in conjunction with Green’s function formalism, transmission spectra of graphene–metal contacts and the voltage-dependent variations of the current and the resistance are obtained. Finally, it is shown that obtained resistance–voltage behaviours of graphene–metal contacts are in consistent with the results reported in the literature and the voltage-dependency of the contact resistance has to be taken into consideration for the nanoscale circuit design process.