Transfer-free graphene synthesis by nickel catalyst dewetting using rapid thermal annealing

We report the transformation of amorphous carbon deposited by pulsed laser deposition (PLD) into free transfer graphene, associated with dewetting of the nickel catalyst film during rapid thermal annealing. Prior to graphene synthesis, dewetting of the pure nickel film is investigated versus thickness and temperature. Then a parametric study of graphene synthesis from an amorphous carbon film 2 nm thick is carried out by varying the starting thickness of the nickel catalyst (25, 50, 150 nm) at a temperature of 900 °C. The graphene layers form on the top surface of the nickel film and at the interface between the nickel film and the SiO2 substrate, due to rapid diffusion of C through the Ni film. The concomitant nickel dewetting process enables exposure of the interfacial graphene while some graphene layers agglomerate on nickel particles. By removing the nickel particles with an acid treatment, interfacial graphene (also called free transfer graphene) was formed directly on the SiO2 substrate, avoiding a time consuming and relatively complicated transfer process. This work paves the way for the control of the number of layers of free transfer graphene using a solid carbon source and a nickel film catalyst.