  Uniform single layer graphene was grown on single-crystal Ir films a few
nanometers thick which were prepared by pulsed laser deposition on sapphire
wafers. These graphene layers have a single crystallographic orientation and a
very low density of defects, as shown by diffraction, scanning tunnelling
microscopy, and Raman spectroscopy. Their structural quality is as high as that
of graphene produced on Ir bulk single crystals, i.e. much higher than on metal
thin films used so far.
