Graphene on SiC(0001) and SiC(0001) surfaces grown via Ni-silicidation reactions

摘要

This paper presents the structure and electronic properties of graphene grown on 6H-SiC(0001) and SiC (0001) surfaces via Ni-silicidation reactions at temperatures around 800 ℃. Silicidation reactions take place at temperature higher_than 400 ℃ for Ni(10 ML)/SiC and a single-phase θ-Ni_2Si(0001)-layer grows epitaxially on SiC(0001) at 500 ℃, whereas a mixed phase silicide-layer is formed on the SiC(0001) substrate. Annealing at 800 ℃ leads to growth of ordered graphite layers on both SiC(0001) and SiC(0001) surfaces with an areal occupation ratio of ～65%, which surround the Ni-silicide islands. High-resolution ion scattering analysis reveals that single- and double-layer of graphite grow on the SiC(0001) and SiC(0001), respectively. The dispersion curve of the n band for the double-layer graphite (DG) on the Si-face lies about 1 eV above that of the single-layer graphite (SG) on the C-face around the Γ-point. The work functions of the SG/SiC(0001) and DG/SiC(0001) are derived to be 5.15 ±0.05 and 4.25 ± 0.05 eV, respectively, which coincide well with the theoretical prediction based on the ab initio calculations. The present results indicate that the electronic states of graphene are influenced by the interaction with supports.