Large contrast enhancement of graphene monolayers by angle detection

TL;DR

This paper demonstrates that adjusting the polarization and angle of optical incidence significantly enhances the visibility of graphene monolayers, facilitating easier detection on various substrates.

Contribution

It introduces a novel angle and polarization-dependent method to improve optical contrast for graphene detection on different substrates.

Findings

Optical contrast of graphene depends strongly on angle and polarization.

Adjusting incident angle and polarization enhances graphene visibility.

Method applicable to new, cleaner substrate materials.

Abstract

Exfoliated graphene monolayers are identified by optical inspection. In order to improve the monolayer detection, we investigate the angle dependence of the optical contrast of graphene on a 90nm SiO$_2$/Si substrate. We observe a significant enhancement of the visibility of graphene by changing the polarization and the angle of optical incidence. This method can be used to detect graphene on new substrate designs such as GaAs/AlAs based materials, which have a much cleaner surface.