Theoretical Study on Epitaxial Graphene Growth by Si Sublimation from SiC(0001) Surface

摘要

The growth of epitaxial graphene on the SiC(0001) surface is theoretically studied by assuming silicon (Si) sublimation from the surface. Our results indicate that a new graphene sheet grows from the interface between the old graphene sheets and SiC substrate, as found in our previous study on graphene growth by carbon (C) deposition. Graphene growth requires overcoming rather lower energy barriers until 0-monolayer graphene (buffer layer) is formed. Further growth toward formation of 1 -monolayer graphene requires overcoming energy barriers higher by about 0.7 eV, which indicates that the growth preferably stops once when 0-monolayer graphene is formed. Compared with the C deposition case, the growth requires overcoming the energy barrier higher by about 0.7eV, which indicates that the graphene growth is more difficult. In addition, the nonuniform growth of surface C aggregates is thought to degrade the quality of the grown graphene. The C-rich condition is therefore important for obtaining high-quality graphene. The experimental graphene growth is considered to proceed similarly to the C deposition case rather than the Si sublimation case.