Edge-Contact Formed by Oxygen Plasma and Rapid Thermal Annealing to Improve Metal-Graphene Contact Resistance

Abstract

Graphene is the first separated 2-dimensional material which has extremely high carrier mobility. The high carrier mobility puts forward stricter requirement on the contact resistance of graphene devices. In this paper, graphene is treated by oxygen plasma with varied time to form different contact type between graphene and metal, especially edge contact which enhances the graphene/metal bond strength and improves the contact resistance. To investigate the effect of thermal annealing on the contact resistance, the graphene devices with different oxygen plasma treatment were annealed by rapid thermal annealing. With the optimized annealing treatment, the average edge contact resistance is reduced by 78.6% to 118 Ω⋅μm, with a minimum value of 92 Ω⋅μm, which is very close to the best results reported so far. For the surface contact devices, thermal annealing resulted in reducing of contact resistance by 48% which is far less than edge contact. Due to the different influence of thermal annealing on various contact type, the edge contact resistance is 37.1% less than surface contact resistance. Since oxygen plasma treatment and rapid thermal annealing both are typical process of regular integrated circuit manufacture flow, the method proposed in the paper could provide an effective and feasible way to optimize the graphene/metal contact, hence promote the performance of future graphene and other two-dimensional material based devices.