Electronic and structural properties of H-intercalated graphene-SiC (0001) interface

In this study, we investigate the changes in electronic and structural properties of a graphene layer deposited on a (root 3 x root 3) R30 degrees SiC (0001) surface before and after hydrogen intercalation using first-principles energy band calculations. Before hydrogen adsorption, the bond distance between the first graphene layer (FGL) and an Si atom on SiC surface is calculated to be 0.2285 nm, which is close to the value reported in the literature. After hydrogen adsorption, the layer distance between SiC surface and FGL tends to increase. The adsorption energy of hydrogen on SiC surface as estimated from the total energy change before and after hydrogen adsorption is relatively small. Thus, we suggest that hydrogen easily bonds to Si dangling bonds on SiC surface. When Si dangling bonds on SiC surface are passivated by hydrogen, the graphene layer on SiC functions as a quasi-free-standing graphene layer, whether the graphene exfoliates or not. Therefore, our results indicate the effectiveness of the hydrogen intercalation technique to create quasi-free-standing epitaxial graphene on Si-face SiC (0001) substrate. (C) 2019 The Japan Society of Applied Physics