  The formation of epitaxial graphene on SiC is monitored in-situ using
low-energy electron diffraction (LEED). The possibility of using LEED as an
in-situ thickness monitor of the graphene is examined. The ratio of primary
diffraction spot intensities for graphene compared to SiC is measured for a
series of samples of known graphene thickness (determined using low-energy
electron microscopy). It is found that this ratio is effective for determining
graphene thicknesses in the range 1 to 3 monolayers. Effects of a distribution
of graphene thicknesses on this method of thickness determination are
considered.
