The growth of epitaxial graphene on silicon carbide (SiC) surfaces is considered to pave the way for graphene-based electronic devices. Graphene can be grown on both polar {0001} surfaces of hexagonal SiC but with properties which are characteristic for the surface polarity. On the Si-face, growth is slower than on the C-face and the crystal lattice of the grown graphene film is aligned with the substrate lattice such that the lattice vectors enclose an angle of 30 degrees. Monolayer graphene can be grown with relatively good homogeneity in argon atmosphere. At low temperature (4 K), these layers show a carrier mobility of up to 29.000 cm2/Vs when the carrier density is tuned close to charge neutrality. However, the carrier mobility is strongly temperature dependent which is not expected from graphene and which therefore should be caused by the interaction with the substrate.
In order to understand the role of interactions with the substrate we have investigated the properties of quasi-freestanding monolayer graphene (QFMLG) obtained by decoupling the covalently bound buffer layer from the substrate by hydrogen intercalation. Annealing of samples covered only by the (6v3×6v3) reconstruction, the so-called buffer layer, in a hydrogen atmosphere breaks the bonds between the SiC(0001) substrate and the chemisorbed graphene layer, which turns into a physisorbed layer with a p-band typical of graphene. In addition to hydrogen it is also possible to intercalate other elements like, e.g. oxygen, fluorine, gold, or germanium between the buffer layer and the SiC substrate.
In my presentation I will briefly summarize the growth and properties of epitaxial graphene on SiC before I survey recent work performed on quasi-freestanding graphene obtained by intercalation. Special emphasis will be put, however, on the system QFMLG/SiC(0001)-H.