Hydrogen Intercalation below Epitaxial Graphene on SiC(0001)
In this report we review how intrinsic drawbacks of epitaxial graphene on SiC(0001) such as n-doping and strong electronic influence of the substrate can be overcome. Besides surface transfer doping from a strong electron acceptor and transfer of epitaxial graphene from SiC(0001) to SiO2 the most promising route is to generate quasi-free standing epitaxial graphene by means of hydrogen intercalation. The hydrogen moves between the (6p3×6p3)R30◦ reconstructed initial carbon (so-called buffer) layer and the SiC substrate. The topmost Si atoms which for epitaxial graphene are covalently bound to this buffer layer, are now saturated by hydrogen bonds. The buffer layer is turned into a quasi-free standing graphene monolayer, epitaxial monolayer graphene turns into a decoupled bilayer. The intercalation is stable in air and can be reversed by annealing to around 900 °C. This technique offers significant advances in epitaxial graphene based nanoelectronics.
Anton J. Bauer, Peter Friedrichs, Michael Krieger, Gerhard Pensl, Roland Rupp and Thomas Seyller
C. Riedl et al., "Hydrogen Intercalation below Epitaxial Graphene on SiC(0001)", Materials Science Forum, Vols. 645-648, pp. 623-628, 2010