Characterisation of as transferred graphene on SiO2 substrates. On left XPS spectrum shows good quality graphene, on right AFM image shows presence of large flakes of graphene with some contamination (marked by circles) and cracks (marked by rectangles). The Raman spectrum of monolayer graphene obtained from the sample is shown in inset.
Kumar et al. Nanoscale Research Letters 2011 6:390 doi:10.1186/1556-276X-6-390