Making graphene visible in transparent dielectric substrates : Brewster angle imaging

• 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.

Subject headings

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

Keyword

Graphene

2D materials

Brewster angle

optical contrast

transparent substrate

Publication and Content Type

ref (subject category)

art (subject category)