Evaluating Tip-Enhanced Raman Spectroscopy as a metrological tool for the determination of the number of graphene layers at the nanoscale

This paper presents a comparative analysis of adjacent single and bilayer graphene samples using micro-Raman spectroscopy and Tip-Enhanced Raman Spectroscopy (TERS) techniques. The measurements were carried out close to the diffraction limit, enabling a highly accurate characterization of the graphene layers by TERS and micro-Raman spectroscopy. Hence, TERS experiments yield significantly improved reliability, ensuring more accurate results, since it reduced the region where the number of layers was unknown from around 500 nm for micro-Raman spectroscopy, with a 1.4 numerical aperture objective, to around 60 nm for TERS.