Monolayer graphite on TaC(111): electronic band structure

The electronic band structure of the monolayer graphite/TaC(111) system was examined using XPS, AES, and ARUPS and the results were compared with predictions of the rigid-band model to determine its validity. The measured graphite σ1 band energy relative to the Fermi energy is −23.0 eV at \gG and the π1 band energy is −10.3 eV at \gG and −3.4 eV at K K. By comparing these values to the results of a linearized augmented-plane-wave calculation of the electronic structure of an isolated graphite monolayer, the qualitative picture of charge transfer from the substrate into the graphite overlayer is confirmed, but the rigidband model is not sufficient to explain the observed binding energy differences between experiment and theory. The degree of hybridization between the electronic bands of TaC and the graphite monolayer is therefore not negligible and should be included in descriptions of the electronic band structures of such systems.