Scanning tunneling spectroscopy on the 6H−SiC(0001)(3 × 3) surface

Abstract

Surface topographic (STM) and spectroscopic (STS) studies have been performed on the Si-terminated 6H-SiC(0001)(3×3) surface using a scanning tunneling microscope (STM) in ultrahigh vacuum. High-quality (3 × 3) overstructures have been prepared as observed by LEED and STM. The regular (3 × 3) surface sites revealed much weaker I(V ) dependences as compared to the defect sites when measured using the constant tip-surface gap technique. The normalized (dI/dV )/(I/V ) vs. V spectra exhibit distinct bands of empty and filled states, which are separated by 1.2 eV for both surface sites, respectively. The results thereby support a Mott-Hubbard-type model as used for the calculation of the density of states. However, the STS spectra become completely featureless in the range of small tip-surface distances and reveal a "metallic"-like Ohmic I-V dependence.

Atomic Structure of SiC Surfaces

“…Spectroscopic STM investigations could confirm these results on an atomic level [86]. For the (3×3) phase the effect was also seen in the experiment [56,106,110]. In this case the Hubbard U is smaller, i.e.…”

State selective electron transport through electronic surface states of6H‐SiC(0001)‐3×3

“…Indeed, three intrinsic surface states are located within the bulk band gap, in which two ͑S 1 and U 1 ͒ arise from strongly correlated electronic states and the third ͑S 2 ͒ has negligible electron correlation effects. 20,21 The morphology of the surface states has a significant influence on the electronic transport properties. Two features have to be distinguished: ͑i͒ the high localization induces strong electronic correlations, which are responsible of a gap opening in the energy distribution and the formation of two distinct surface states U 1 and S 1 , the so-called Mott-Hubbard electronic states, and ͑ii͒ the weak overlap between neighboring silicon adatoms is responsible for a reduced electronic mobility along the semiconductor surface through U 1 or S 1 .…”

Synchrotron x-ray photoelectron spectroscopy study of hydrogen-terminated6H−SiC{0001}surfaces

“…A majority of these studies dealt with the Si-rich [1][2][3][4][5][6][7][8][9][10] (3ϫ3) and (ͱ3ϫͱ3)R30°͑Refs. 6 -24͒ reconstructions on 4H-and 6H-SiC(0001), the (3ϫ3) reconstruction 5,25 on 6H-SiC(0001 ), and the oxygen induced silicate adlayer reconstructions on 4H-and 6H-SiC͕0001͖ surfaces.…”