In situ control of dewetting of Cu thin films in graphene chemical vapor deposition

• A method to monitor dewetting of Cu thin films during CVD is proposed.
• Measurement of typical time constants of dewetting dynamics.
• Analysis of the role of gas composition and pressure on dewetting phenomena.
• The importance of pre-deposition step in graphene CVD onto Cu thin films is featured.

Chemical vapor deposition (CVD) on Cu thin films is a promising approach for the large area formation of graphene on dielectric substrates, but a fine control of the deposition parameters is required to avoid dewetting of the Cu catalyst. In this paper we report on the study of the Cu dewetting phenomena by monitoring the intensity of the infra-red emission from the film surface during rapid thermal CVD of graphene. The reduction of Cu film coverage consequent to dewetting is detected as a variation of sample's emissivity. Results indicate three time constants of dewetting, describing three typical stages, hole formation, propagation and ligament breakup. Slowing the first incubation stage by tuning pressure in the chamber allows for an effective surface activation resulting in the deposition of graphene at temperatures lower than those in the case of Cu foils.