Calculated dependence of few-layer graphene on secondary electron emissions from SiC

A decrease in the yield of secondary electron emissions of SiC, δ, with an increased number of graphene layers is evaluated from a two-dimensional (2D) transmission function of secondary electrons (SEs) across an increased potential barrier. For incident keV-electrons, a decrease of approximately 5% in δ is estimated for an increase in electron affinity, χ, of 0.1 eV suggesting the use of scanning electron microscopes for in situ thickness imaging of graphene devices with a lateral resolution in the nanometer range. Some possible improvements in contrast are indicated. The present approach also holds for SEs that are induced by photons to image local changes of χ on other substrates.