Si beam-assisted graphitization of SiC (0001)

We have performed a study of thermal graphitization of SiC (0001) surface in the high-purity molecular beam of Si atoms obtained from a controllable source. With the aid of Si beam, we have been able to achieve the semi-equilibrium reaction conditions and to control the growth rate of graphene film freely until complete stop of the graphitization, at the test temperature of 1350 degrees C. Samples treated in Si beam are characterized by larger and homogeneous areas of graphene having uniform thickness, and much improved crystallographic ordering. This is attributed mainly to the improved buffer layer structure. The buffer layer shows neither disordered regions, nor point defects, which are prevalent in UHV-annealed samples. Significantly smaller concentrations of other surface defects are also observed. The used approach is a promising alternative to more commonly used buffer gas graphitization methods. Apart from the precise control for process parameters and very high process purity, it also allows for a co-deposition of other atoms at the growth stage.