We present a micro-Raman spectroscopy study on single- and few layer graphene (FLG)
grown on the silicon terminated surface of 6H-silicon carbide (SiC). On the basis of the 2D-line (light
scattering from two phonons close to the K-point in the Brillouin zone) we distinguish graphene
mono- from bilayers or few layer graphene. Monolayers have a 2D-line consisting of only one
component, whereas more than one component is observed for thicker graphene layers. Compared to
the graphite the monolayer graphene lines are shifted to higher frequencies. We tentatively ascribe the
corresponding phonon hardening to strain in the first graphene layer.