  We perform local nanoscale studies of the surface and interface structure of
hydrogen intercalated graphene on 4H-SiC(1000). In particular, we show that
intercalation of the interfacial layer results in the formation of quasi-free
standing one layer graphene (QFS 1LG) with change in the carrier type from n-
to p-type, accompanied by a more than four times increase in carrier mobility.
We demonstrate that surface enhanced Raman scattering (SERS) reveals the
enhanced Raman signal of Si-H stretching mode, which is the direct proof of
successful intercalation. Furthermore, the appearance of D, D+D' as well as C-H
peaks for the quasi-free standing two layer graphene (QFS 2LG) suggests that
hydrogen also penetrates in between the graphene layers to locally form C-H sp3
defects that decrease the mobility. Thus, SERS provides a quick and reliable
technique to investigate the interface structure of graphene which is in
general not accessible by other conventional methods. Our findings are further
confirmed by Kelvin probe force microscopy and X-ray photoelectron
spectroscopy.
