We demonstrate how self-assembled monolayers of aromatic molecules on copper substrates can be converted into high-quality single-layer graphene using low-energy electron irradiation and subsequent annealing. We characterize this two-dimensional soli
d state transformation on the atomic scale and study the physical and chemical properties of the formed graphene sheets by complementary microscopic and spectroscopic techniques and by electrical transport measurements. As substrates we successfully use Cu(111) single crystals and the technologically relevant polycrystalline copper foils.
We report on the detection and charge distribution analysis for nitrogen substitutional dopants in single layer graphene membranes by aberration-corrected high-resolution transmission electron microscopy (HRTEM). Further, we show that the ionicity of
single-layer hexagonal boron nitride can be confirmed from direct images. For the first time, we demonstrate by a combination of HRTEM experiments and first-principles electronic structure calculations that adjustments to the atomic potentials due to chemical bonding can be discerned in HRTEM images. Our experiments open a way to discern electronic configurations in point defects or other non-periodic arrangements or nanoscale objects that can not be analyzed in an electron or x-ray diffraction experiment.
