Contact resistance for "end-contacted" metal-graphene and metal-nanotube interfaces from quantum mechanics

In this paper, we predict the current-voltage (I-V) characteristics and contact resistance of "end-contacted" metal electrode-graphene and metal electrode-carbon nanotube (CNT) interfaces for five metals, Ti, Pd, Pt, Cu, and Au, based on the first-principles quantum mechanical (QM) density functional and matrix Green's function methods. We find that the contact resistance (normalized to surface C atoms) is 107 kΩ for Ti, 142 kΩ for Pd, 149 kΩ for Pt, 253 kΩ for Cu, and 187 kΩ for Au. This can be compared with the contact resistance (per C) for "side- contacted" metal-graphene or metal-CNT interfaces of 8.6 MΩ for Pd, 34.7 MΩ for Pt, 630 MΩ for Cu, etc. Those are in good agreement with available experimental results, 40.5 MΩ for Pt, for example. Thus, compared to the values for side-contacted interfaces from QM, we find a decrease in contact resistance by factors ranging from 6751 for Au and 2488 for Cu, to 233 for Pt and 60 Pd, to 8.8 for Ti. This suggests a strong advantage for developing technology to achieve "end-contacted" configurations.