Photoemission electron microscopy of graphene

A study of chemical vapor deposited graphene on copper foil is conducted using an aberration-corrected photoemission electron microscope (PEEM). We demonstrate the efficacy such a PEEM has in identifying multi-layer graphene, defects and cracking. A model is developed to describe the observed reduction in photoemission rate where electrons originate from the copper foil and scatter through the graphene. A survey of several multi-layer feature line profiles demonstrates the reduced photoemission rate as the number of graphene layers increases. A mean-free-path length of $l=3.8\pm0.8$ nm is inferred assuming the layer spacing in graphene is $\Delta z=0.35$ nm. The PEEM's high spatial resolution and surface sensitivity combined with no electron beam damage are promising for characterizing biosensors and other nanoscale graphene devices.