Highly n-doped graphene generated through intercalated terbium atoms

We obtained highly n-type doped graphene by intercalating terbium atoms between graphene and SiC(0001) through appropriate annealing in UHV. After terbium intercalation angle-resolved-photoelectron spectroscopy (ARPES) showed a drastic change in the band structure around the K-points of the Brillouin zone: the well-known conical dispersion band of a graphene monolayer was superposed by a second conical dispersion band of a graphene monolayer with an electron density reaching 10¹⁵cm^-2. In addition, we demonstrate that atom intercalation proceeds either below the buffer layer or between the buffer layer and monolayer graphene. The intercalation of terbium below a pure buffer layer led to the formation of a highly n-doped graphene monolayer decoupled from the SiC substrate, as evidenced by ARPES and XPS measurements. The band structure of this highly n-doped monolayer graphene showed a kink (a deviation from the linear dispersion of the Dirac-cone) which has been associated to electron-phonon coupling constant one order of magnitude larger than those usually obtained for graphene with intercalated alkali metals.