A sensitive reflection method for optical diagnostics of graphene layers

Simple reflection diagnostics possibilities of graphene layers on dielectric and semiconductor substrates at the Brewster angle are analyzed. The analysis is based on a numerical simulation. It is shown that in the vicinity of the Brewster angle optical contrast (differential reflectance) of graphene flakes on bare substrates is strong and significantly different for graphene flakes with different number of graphene layers, which allows for a simple identification of the number of layers in the graphene sheet. Another way to determine the number of graphene layers in a graphene sheet by using the shift of the p-polarized light reflectance minima (quasiBrewster angle) as a function of the number of graphene layers is also proposed.