CVD Formation of Graphene on SiC Surface in Argon Atmosphere

We investigate the microscopic processes leading to graphene growth by the chemical vapor deposition of propane in the argon atmosphere at the SiC surface. Experimentally, it is known that the presence of argon fastens the dehydrogenation processes at the surface, in high temperature of about 2000K. We perform ab-initio calculations, at zero temperature, to check whether chemical reactions can explain this phenomenon. Density functional theory and supporting quantum chemistry methods qualitatively describe formation of the graphene wafers. We find that the 4H-SiC(0001) surface exibits large catalytic effect in the adsorption process of hydrocarbon molecules, this is also supported by preliminary molecular dynamics results. Existence of the ArH+ molecule, and an observation from the Raman spectra that the negative charge transfers into the SiC surface, would suggest that presence of argon atoms leads to a deprotonization on the surface, which is necessary to obtain pure carbon add-layer. But the zero-temperature description shows that the cold environment is insufficient to promote the argon-assisted surface cleaning.