Conductance through Nanometer-scale Metal-to-Graphite Contacts

Abstract

The metal/graphite interface is interesting due to the typically large disparity in the characteristics of the electronic structure (e.g. Fermi wavelength and Fermi energy) and dimensionality (3D in the metal versus quasi-2D in graphite). The goal of this work is to determine how the contact conductance to graphite depends on the metal contact area for nanometer-scale contacts. From this we deduce the effect of electronic screening in the graphite. Three different metals were chosen for this work: Solid Cu and Al, and liquid Ga. Liquid Ga provided a unique opportunity to reduce the effect of mechanical interactions to near zero, while Cu and Al were chosen for their different electronic structures. At the interface between the metal and graphite, the large Fermi wavevector of Al should allow phase matching of Al states to those in graphite, while the Cu Fermi surface lies inside of all available graphite wavevector states.