Imaging the interface states of epitaxial graphene layers on 6H-SiC

Single and bi-layer graphene were epitaxially grown on both the Si- and C-terminations of 6H-SiC. The energy dependence and spatial distribution of their local density of states were investigated using scanning tunneling microscopy and spectroscopy. Of particular interest is the rt3xrt3 reconstructed interface state. Atomically resolved topographs and dI/dV images show clear differences between the single and bi-layer graphene at different length scales. These results will be compared to the electronic and structural properties obtained by first principles calculations.