On the effect of the spontaneous polarization of a SiC substrate on a buffer layer and quasi-free single-sheet graphene

The study is concerned with two problems: (i) the influence of the spontaneous polarization of a SiC substrate on the binding energy of silicon and carbon atoms of the substrate with carbon atoms of the buffer layer and (ii) the role of the spontaneous polarization of the SiC substrate in the doping of quasi-free single-sheet graphene. In case (i), it is shown that spontaneous polarization has practically no effect on the substrate-(buffer layer) binding energy. In case (ii), spontaneous polarization has a profound qualitative effect, only if the Fermi level in the system is almost coincident with the Dirac point of graphene. All estimates are obtained in the context of simple models. The 6H-SiC$\{0001\}$ and 4H-SiC$\{0001\}$ polytypes are studied as the substrates.