An Improved Method for Transferring Graphene Grown by Chemical Vapor Deposition

In this paper, we report an improved transfer of graphene by directly picking up the graphene with target substrates and the comparison of such transferred graphene samples with other graphene samples transferred by the commonly used "PMMA-based transfer" method. Raman spectroscopy studies show that this "direct transfer method" does not degrade the graphene structure and field effect transistor measurements show that it does not introduce any extra doping in graphene; in contrast, PMMA-based transfer samples have strong n-type doping. We also find that graphene samples achieved by this direct transfer method show higher mobility than graphene obtained from the PMMA-based transfer method.