Identification of epitaxial graphene domains and adsorbed species in ambient conditions using quantified topography measurements

Abstract

We discuss general limitations of topographical studies of epitaxial graphene in ambient conditions, in particular, when an accurate determination of the layers thickness is required. We demonstrate that the histogram method is the most accurate for measurements of small vertical distances (<0.5 nm) and generally should be applied to epitaxial graphene and similar types of samples in order to get the correct and reproducible values. Experimental determination of the step height between different domains of epitaxial graphene shows excellent agreement with the predicted values once the adsorption of a 2D monolayer is taken into account on top of the one layer graphene. In contrast to general limitations of AFM topography, electrostatic force microscopy imaging allows a straightforward identification of domains of epitaxial graphene of different thickness.