Scanning Tunneling Spectroscopy of Oxidized 6H-SiC Surfaces

Scanning tunneling microscopy and spectroscopy has been used to study the electronic states of oxidized 6H-SiC interfaces. The SiC surfaces were oxidized by annealing in an ultra-high vacuum chamber at 600-800ºC under 1×10^-7 Torr pressure of molecular oxygen. Tunneling spectra revealed two dominant states at –1.8 and 1.5 eV relative to the Fermi level, which lie outside the band gap region but are inhomogeneously broadened such that they extend into the gap, together with additional features within the band gap.