Effect of intercalated hydrogen on the electron state of quasi-free graphene on a SiC substrate

To judge the role of intercalated hydrogen in the doping of quasi-free epitaxial graphene, two systems, specifically, (i) the graphene–N$H$-SiC$\{0001\}$ and (ii) graphene–hydrogen single layer–N$H$-SiC$\{0001\}$ structures (N = 4, 6) are considered. In case (i), the shift of the Dirac point of epitaxial graphene is induced by the electrostatic potential of spontaneous polarization of the substrate; in case (ii), the shift is due to the field of a double electrical layer formed because of the absorption of hydrogen atoms. It is shown that, in case (ii) compared to case (i), the concentration of holes in graphene is higher and the concentration of electrons is lower. This result is consistent with the currently available experimental data.