Semi-dry transfer of CVD graphene on Si: surface morphology and electronic properties

To expand the possible applications, chemical vapor deposition grown graphene needs to be transferred to appropriate substrates such as a silicon wafer. Although enormous efforts have been devoted to transfer graphene to various substrates using many different methods, the quality of the final product is still insufficient. We develop a new process named semi-dry transfer, which combines wet etching and dry transfer to obtain graphene with a clean interface with the substrate. For this purpose, an adhesive tape is attached to a sacrificial polymer deposited on the synthesized graphene, which allows the graphene to be easily manipulated so that it can be carefully cleaned before being precisely transferred onto target substrates, here silicon (Si) surfaces. We used this technique to transfer up to 4 × 4 cm² of graphene onto SiO₂/Si substrates. Using various analysis techniques such as low energy electron diffraction, scanning electron microscopy, scanning tunneling microscopy/spectroscopy, Raman, Auger electron and X-ray photoelectron spectroscopies, we demonstrate that our transferred graphene on Si is continuous, clean and that it is very promising for device fabrication. Graphene transistors show transport properties comparable with the state-of-the-art.