Study of the Electronic and Optical Properties of Graphene/4H-SiC Heterostructure*

Monolayer epitaxial graphene (EG) is a suitable candidate for a variety of electronic applications. One advantage of EG growth on the Si face of SiC is that it develops as a single crystal, as does the layer below, referred to as the interfacial buffer layer (IBL), whose properties include an electronic bandgap. Though much research has been conducted to learn about the electrical properties of the IBL, not nearly as much work has been reported on the optical properties of the IBL. Previously, combining the experimental measurements and density functional theory (DFT), we have studied the electronic property and dielectric function of the heterostructure bilayers. We have found that the dielectric function of the IBL, the permittivity of the material, is within the energy range of 1 eV to 8.5 eV. DFT results revealed the wave nature of the IBL graphene, which matches the experimental results. According to our new DFT calculations, the length of the wave is 6.19 Å which is a 3x3x1 supercell for the IBL graphene. Additionally, we have found that the formation of the wave entirely depends on the lattice mismatch between graphene, SiC, and mechanical strain.