High-throughput graphene imaging on arbitrary substrates with widefield Raman spectroscopy.

Raman spectroscopy has been used extensively to study graphene and other sp(2)-bonded carbon materials, but the imaging capability of conventional micro-Raman spectroscopy is limited by the technique's low throughput. In this work, we apply an existing alternative imaging mode, widefield Raman imaging (WRI), to image and characterize graphene films on arbitrary substrates with high throughput. We show that WRI can be used to image graphene orders of magnitude faster than micro-Raman imaging allows, while still obtaining detailed spectral information about the sample. The advantages of WRI allow characterization of graphene under conditions that would be impossible or prohibitively time-consuming with other techniques, such as micro-Raman imaging or reflected optical microscopy. To demonstrate these advantages, we show that WRI enables graphene imaging on a large variety of substrates (copper, unoxidized silicon, suspended), large-scale studies of defect distribution in CVD graphene samples, and real-time imaging of dynamic processes.