The role of SiC as a diffusion barrier in the formation of graphene on Si(111)

In this paper, we investigate the role of SiC as a diffusion barrier for Si in the formation of graphene on Si(111) via direct deposition of solid-state carbon atoms in ultra-high vacuum. Therefore, various thicknesses of the SiC layer preformed on the Si substrates were produced in order to evaluate its influence on the quality of graphene formation at different substrate temperatures from 900 °C to 1100 °C. At a given temperature of 1100 °C, we found that a thicker SiC layer can suppress silicon-out diffusion from the substrate and improve the structural quality of the graphene layer. The samples were analyzed by low energy electron diffraction, Auger electron spectroscopy, X-ray photoemission spectroscopy, Raman spectroscopy, and scanning tunneling microscopy.