Recently we have obtained atomic resolution topography and spectroscopy images of graphene on hexagonal boron nitride. We have found that the graphene is extremely flat, about 10 times flatter than on silicon dioxide. The 1.8% mismatch between the graphene and boron nitride lattices causes a Moire pattern to form based on the relative orientation of the two lattices. On the right is an example of a topographic image showing the hexagonal lattice of graphene and a longer wavelength Moire pattern.
Beyond the topography measurements, we have also mapped the local density of states in the graphene. We have found that the boron nitride reduces the density flucuations (electron and hole puddles) by two orders of magnitude compared to graphene on silicon dioxide. The image below shows a comparision of the potential fluctuations in graphene on silicon oxide (left) and boron nitride (right). We observe that there are less puddles on boron nitride and they have much smaller potential variation. This work was published in Nature Materials