Preparation and characterisation of carbon-free Cu(111) films on sapphire for graphene synthesis

This work presents an investigation of carbon formed on polycrystalline Cu(111) thin films prepared by ion beam sputtering at room temperature on c-plane Al₂O₃ after thermal treatment in a temperature range between 300 and 1020°C. The crystallinity of the Cu films was studied by XRD and RBS/channeling and the surface was characterised by Raman spectroscopy, XPS and AFM for each annealing temperature. RBS measurements revealed the diffusion of the Cu into the Al₂O₃ substrate at high temperatures of > 700°C. Furthermore, a cleaning procedure using UV ozone treatment is presented to remove the carbon from the surface which yields essentially carbon-free Cu films that open the possibility to synthesize graphene of well-controlled thickness (layer number).