3 × 3)-R30° surface the occupied and unoccupied
Mott-Hubbard bands are found with a splitting U=2.4±0.1 eV.
A long-lived exciton between the Mott-Hubbard bands is identified
with a binding energy of ~0.7 eV.
Two-photon photoemission has been used to study the electronic
structure of the valence and conduction bands at SiC(0001)
surfaces. The various surface reconstructions show distinctly
different spectra and work functions. The ionization energy is
found independent of polytype and surface reconstruction to
6.9±0.2 eV. For the (3 × 3)-R30° surface the occupied and unoccupied
Mott-Hubbard bands are found with a splitting U=2.4±0.1 eV.
A long-lived exciton between the Mott-Hubbard bands is identified
with a binding energy of ~0.7 eV.