Surface tension traction transfer method for wafer-scale device grade graphene film

The integrity and cleanliness of graphene film is the core of graphene devices. However, the cleanliness and integrity of the graphene film can only be ensured when the transferred film area is small (less than 2╳2 cm2), which leads to the extremely low preparation efficiency of graphene devices and limits its industrialization applications. But, the integrity and cleanliness of the graphene film will decrease with the increase of the transfer film area. Therefore, the clean and intact transfer of large area graphene films is extremely difficult, which limits the performance and development of graphene electronic devices. Hence, a wafer-scale(6-inch), intact and clean transfer method (Surface tension traction method) of chemical vapor deposition (CVD) copper-based monolayer, multilayer graphene and single crystals graphene are proposed, which is suitable for various target substrate (rigid substrate, such as:SiO2/Si, GaN, glass etc. or flexible substrate, such as PI, PET, PEN, etc.). The use of the watch glass ensures that the graphene film is not directly contacted with the transfer medium (slides, glass or silicon wafers) when the film is transferred between various solutions. And the surface tension of the water can ensure that the graphene is spread on the water surface, which minimizing the probability of graphene breakage, wrinkles and contamination. This also directly greatly reduces the residue of the PMMA layer. The average of 62500 spots of Raman spectrum peak intensity ratios (ID/IG) is only 0.02318, The average hole mobility of GFETs prepared from graphene transferred can reach 3438 ± 84 cm2/Vs, which reveals the outstanding quality and uniformity of graphene transferred. The graphene transferred is expected to be applied in the fields of transparent, conductive electrodes, flexible films, electronic devices, heat dissipation and anti-corrosion, etc, to promote the industrial production of CVD graphene films.