▎ 摘　　要

A decrease in the yield of secondary electron emissions of SiC, delta, 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 delta is estimated for an increase in electron affinity, chi, 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 chi on other substrates. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3534805]