ELECTRONIC-STRUCTURE OF 6H-SIC(0001)

An electronic structure investigation of Si-terminated 6H-SiC(0001) is reported. The valence-band structure is investigated using photoemiss ion and synchrotron radiation. Recorded valence-band spectra are compa red with the partial densities of states obtained in a full-potential linearized augmented plane-wave band-structure calculation. Lower-lyin g C 2s states give the dominant contribution in spectra recorded at hi gher photon energies, while higher-lying hybridized C 2p and Si 3s and 3p states dominate at lower photon energies. Assignment of different structures is made from the variation observed in relative intensity w ith photon energy. The overall agreement between calculated and experi mental results is quite satisfactory considering that the experimental studies were conducted on the root 3x root 3-R30 degrees and 6 root 3 x6 root 3-R30 degrees reconstructed surfaces, while the calculated res ults represent the bulk density of states. Significant differences are observed, however. A surface state is identified on the root 3 surfac e, at 1.3 eV below the Fermi level, and its origin is discussed.