Effect of interfacial Ni between graphene and Pt/Au on reducing specific contact resistivity

Abstract

Low contact resistance between graphene and metals is of critical importance to fabricate high-performance graphene-based devices. In this work, the effect of interfacial Ni of different thicknesses, i.e. 0 nm, 1 nm, 2 nm, 4 nm and 5 nm, on the contact resistance of graphene and Pt/Au was investigated systematically. As-transferred graphene grown on Cu foil using a PMMA-assisted process was characterized by optical, Raman and atomic force microscopy. As to the extraction of contact resistance, conventional transmission line method structures were fabricated and measured sophisticatedly. Rapid thermal annealing at different temperatures, i.e. 400 °C, 450 °C, 500 °C, 550 °C and 600 °C, was also performed to determine the optimum temperature and thickness of Ni as an interfacial layer. It was found that an interfacial Ni with proper thickness and thermal treatment is beneficial in reducing contact resistance between graphene and Pt/Au. The role of interfacial Ni is also discussed.