Making graphene visible in transparent dielectric substrates: Brewster angle imaging
2015 (English)In: 2D Materials, Vol. 2, no 3Article in journal, Letter (Refereed) Published
The visibility of graphene is greatly increased by illuminating samples deposited on transparent dielectrics at the substrates’ Brewster angle. Using a commercial ellipsometer, the reflectivity of monolayers of CVD graphene is found to be up to 33 times higher than that of the substrate, i.e., an optical contrast as high as 3200% is obtained, more than 380 times higher than with standard optical microscopy. Also, with a simpler, homemade, experimental setup, a 1400% optical contrast was measured for a monolayer of CVD graphene and linear features as small as ~20 μm were visible in a monolayer, while ~6×17 μm2 trilayers could still be imaged in exfoliated samples. It is also shown that the reflectance/transmittance ratio increases quadratically with the number of graphene layers, which may allow for counting layer numbers and identifying wrinkles and folds in transferred samples.
Place, publisher, year, edition, pages
Institute of Physics (IOP), 2015. Vol. 2, no 3
Graphene, 2D materials, Brewster angle, optical contrast, transparent substrate
IdentifiersURN: urn:nbn:se:kth:diva-179733OAI: oai:DiVA.org:kth-179733DiVA: diva2:888204
QC 201601202015-12-222015-12-222016-01-20Bibliographically approved