A simple and clean transfer method of chemical-vapor deposited graphene on Cu

A simple, scalable, clean and fast transfer process of graphene (Gr) grown on Cu by chemical vapor deposition onto an arbitrary substrate is desirable for practical applications of Gr. The conventional transfer method using poly(methyl methacrylate) (PMMA) as a supporting layer leaves residues on the Gr surface after transfer and takes a long time due to the slow wet etching step of the Cu substrate. In our approach, the PMMA supporting layer is replaced by a screen protector film composed of polyethylene terephthalate (PET)/silicone stacks that gives a clean surface through the weak dispersive adhesion between the film and CVD Gr/Cu. In addition, the typical wet etchants such as FeCl₃ and ammonium persulfate used as Cu removers are also replaced with H₂ bubbling for the separation of Gr from the Cu substrate to enhance the cleanliness by preventing the doping of the Gr caused by wet etchants. It takes less than an hour for the whole process of Gr transfer, which makes this method convenient and efficient. Various analyses showed that the surface and electrical properties of the Gr transferred by this method are superior to those of Gr transferred by conventional PMMA-mediated transfer.