High-resolution, spatially-resolved surface potential investigations of high-strength metallurgical graphene using scanning tunnelling potentiometry

Abstract

Here we present an approach to measure the surface potential distribution of specimens using scanning tunnelling potentiometry with high potential gradients and relatively low sample bias. A special design of test structures containing pre-patterned electrodes was employed. Material of interest is transferred onto test structures, so that additional material processing during the investigations can be avoided. The utility of this solution is assessed in an investigation of high–strength metallurgical graphene. A maximum potential gradient of 49.2 V/mm was obtained by applying a sample bias of 0.8 V. Values of the resistivity of graphene inclusions up to 450 Ω·μm were observed. The influence of inclusions could be reduced by performing controllable post-transfer annealing. This could remove polymer residue from the graphene surface, but may introduce additional features in the Raman spectra. Work functions of 4.68–4.70 eV were estimated using Kelvin probe force microscopy.