First-Principles Calculation Study of Epitaxial Graphene Layer on 4H-SiC (0001) Surface

摘要

We performed first-principles energy-band calculations based on the generalized gradient approximation (GGA) in the Perdew-Burke-Ernzerhof (PBE) functional to determine the electronic structure of the graphene/SiC (0001) interface with a √3 × √3 SiC periodicity.In the calculations, a structural model of graphene on a 4H-SiC substrate was constructed using a slab that contained four bilayers with dangling bonds terminated by hydrogen on the another surface of the slab.It is well known that the GGA method tends to overestimate the graphene layer spacing (GLS) when compared with experimental values reported previously.We included van der Waals interactions in the present calculations with the PBE-GGA exchange-correlation functional using the Grimme and Tkatchenko-Scheffler methods.The former scheme was observed to well reproduce the experimental value of the GLS compared with the latter one.Finally, the influence of Si and C vacancies on the electronic structure of the graphene/4H-SiC (0001) interface was investigated using these methods.