A comparative study of Ge/Au/Ni/Au-based ohmic contact on graphene

Abstract

Superior graphene—metal contacts can improve the performance of graphene devices. We report on an experimental demonstration of Ge/Au/Ni/Au-based ohmic contact on graphene. The transfer length method (TLM) is adopted to measure the resistivity of graphene-metal contacts. We designed a process flow, which can avoid residual photoresist at the interface of metal and graphene. Additionally, rapid thermal annealing (RTA) at different temperatures as a post-processing method is studied to improve graphene—metal contact. The results reveal that the contact resistivity of graphene and Ge/Au/Ni/Au can reach 10−5 Ω·cm2 after RTA, and that 350 °C is optimum annealing temperature for the contact of graphene—Ge/Au/Ni/Au. This paper provides guidance for fabrication and applications of graphene devices.