Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 106: Graphene: Interaction with the Substrate (organized by HL)
TT 106.2: Talk
Friday, April 4, 2014, 11:30–11:45, POT 081
The (3×3)-SiC(1 1 1) reconstruction: Surface phase equilibria near the graphene formation regime on 3C-SiC(1 1 1) — •Lydia Nemec1, Florian Lazarevic2, Patrick Rinke1, Volker Blum3, and Matthias Scheffler1 — 1Fritz-Haber-Institut der MPG, Berlin — 2AQcomputare GmbH, Chemnitz — 3MEMS Department, Duke University, Durham, NC, USA
To refine the growth quality of epitaxial graphene on the C-side of SiC and improve the resulting electronic character of these films, it is important to understand the atomic- and electronic-structure of the interface. A phase mixture of different surface phases is observed just when surface graphitization first sets in. However, the atomic structure of some of the competing surface phases, as well as of the SiC-graphene interface, is unknown.
We performed a density functional theory study on the C-side of the polar SiC(1 1 1) surface using the all-electron, numeric, atom-centered basis function code FHI-aims. The formation energy of different reconstructions and model systems for the interface is presented within the thermodynamically allowed range.
The surface energies of the known (2×2) phase is compared with several structural models of the (3×3) phase proposed in the literature. In comparison all the previously suggested (3×3) models are higher in energy than the known (2×2) phase. We present a new model for the (3×3) reconstruction. Its formation energy crosses that of the (2×2) phase just at the carbon rich limit of the chemical potential, which could explain the observed phase mixture.