Scanning Tunneling Spectroscopy of Mott-Hubbard States on the 6H-SiC(0001) √3 ×√3 Surface

Scanning tunneling spectra have been measured on the $6H$-SiC(0001) $\sqrt{3}\times \sqrt{3}$ surface for both $p$- and $n$-type materials. With the use of exceptionally low tunnel currents, the tunneling spectra reveal distinct bands of empty and filled states, separated by 2.0 eV. The states are located at the same spatial position, thereby supporting a silicon adatom model which predicts a Mott-Hubbard-type density of states.