Resistivity of Rotated Graphite-Graphene Contacts

Robust electrical contact of bulk conductors to two-dimensional (2D) material, such as graphene, is critical to the use of these 2D materials in practical electronic devices. Typical metallic contacts to graphene, whether edge or areal, yield a resistivity of no better than 100 Omega mu m but are typically >10 k Omega mu m. In this Letter, we employ single-crystal graphite for the bulk contact to graphene instead of conventional metals. The graphite contacts exhibit a transfer length up to four-times longer than in conventional metallic contacts. Furthermore, we are able to drive the contact resistivity to as little as 6.6 Omega mu m(2) by tuning the relative orientation of the graphite and graphene crystals. We find that the contact resistivity exhibits a 60 degrees periodicity corresponding to crystal symmetry with additional sharp decreases around 22 degrees and 39 degrees, which are among the commensurate angles of twisted bilayer graphene.