An Investigation of PDMS Stamp Assisted Mechanical Exfoliation of Large Area Graphene

We report on a study of a viscoelastic polymer stamp-based mechanical exfoliation technique capable of yielding large area (similar to square centimeters or larger) graphene layers from a highly ordered pyrolytic graphite (HOPG) substrate by manipulating the adhesion properties of a Polydimethylsiloxane (PDMS) stamp and other key process parameters. In particular, the effects of stamp adhesion, normal contact force, and dwell time on the exfoliation force, layer thickness, and graphene surface morphology are studied. Experiments show that the process is capable of exfoliating relatively large (up to 12x 12 mm(2)) graphene layers under certain conditions. The exfoliated layers, albeit of varying thickness, have regions that are tens of nanometer thick and contain various topographical features such as bubbles, wrinkles, and compressed regions. This work serves as the first step toward developing a scalable production method for large area graphene and other layered materials of interest.