Surface morphology and characterization of thin graphene films on SiC vicinal substrate

In this Brief Report we present a study of a 6H-SiC(0001) vicinal substrate annealed at various temperatures under ultrahigh vacuum. By combining x-ray photoelectron spectroscopy and atomic force microscopy, we investigated the morphology and the chemical surface changes accompanying the formation of graphene sheets. After annealing at $1100°\text{C}$ step/terrace structures of the SiC substrate are clearly identified and a terrace widening is observed due to step bunching up. At $1300°\text{C}$ approximately two graphene layers are formed and the surface steps completely disappear.

Figure 1

(Color online) A series of the AFM images and line sections (insert) displaying the surface evolution of the SiC during UHV annealing: (a) AFM images of the SiC at $1100°\text{C}$, (b) $1200°\text{C}$, and (c) $1300°\text{C}$.

Figure 2

(a) $\text{Si}2p$ XPS spectra of 6H-SiC(0001) surfaces; (b) $\text{C}1s$ XPS spectra of 6H-SiC(0001) surfaces annealed at different substrate temperatures at normal incidence.

Figure 3

(Color online) (a) $\text{C}1s$ XPS spectra of 6H-SiC(0001) surfaces annealed at $1300°\text{C}$ at normal incidence and grazing incidence; (b) XPS spectra of the $\text{C}1s$ core level from the SiC surfaces annealed at $1300°\text{C}$ at grazing incidence $\left(\phi =70°\right)$; for each spectrum we give the experimental data after background subtraction and the decomposition with bulk and two surfaces components identified by $B$, $G$, and $S$, respectively.