Measurement of electrical contact resistance at nanoscale gold-graphite interfaces

Abstract

An approach to measuring electrical contact resistance as a direct function of the true contact size at the nanoscale is presented. The approach involves conductive atomic force microscopy (C-AFM) measurements performed on a sample system comprising atomically flat interfaces (up to several hundreds of nanometers in lateral size) formed between gold islands and a highly oriented pyrolytic graphite (HOPG) substrate. The method overcomes issues associated with traditional C-AFM such that conduction can be correlated with a measurable true, conductive contact area. Proof-of-principle experiments performed on gold islands of varying size point toward an increasing contribution of the island-HOPG junction to the measured total resistance with decreasing island size. Atomistic simulations complement and elucidate experimental results, revealing the maximum island size below which the electrical contact resistance at the island-HOPG junction can be feasibly extracted from the measured total resistance.