Polarized light microscopy of chemical-vapor-deposition-grown graphene on copper

Linearly polarized light microscopy (PM) revealed that graphene grown by chemical vapor deposition (CVD) on stepped Cu substrate may appear colored. The coloration is associated with the coupling of the light of 450-600nm into propagating mode in the graphene layer when the electric vector ( E → ) of polarized light is parallel with the step edges and with the scattering when the E → is normal to the step edges. PM is an inexpensive, fast, and contamination free method to efficiently visualize graphene and to map the step structure of Cu substrates used for large area CVD growth of graphene.