Enhancing the visibility of graphene on GaAs

We present a method to enhance the visibility of graphene on GaAs. Therefore the samples are spin-coated with e-beam resist of well defined thickness. For determination of the optimal thickness, the optical contrast is calculated taking into account thicknesses and refractive indices of the layers as well as the sensitivity of the human eye. The visibility studies of single-layer graphene on GaAs are accompanied by Raman spectroscopy and magnetotransport measurements. We demonstrate that it is possible to detect graphene flakes by optical microscopy and determine the number of graphene layers by measuring the Raman signal through the resist layer. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3660584]