Published in Appl. Phys. A 72 [Suppl.], S193 (2001).
Recent Developments in Scanning Tunneling Spectroscopy of
Semiconductor Surfaces
R. M. Feenstra, V. Ramachandran and Huajie Chen
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
Abstract
Several recent developments in scanning tunneling spectroscopy (STS)
of semiconductor surfaces are reviewed. First, the normalization of
spectra is discussed, which for the Si(111)2x1 surface is found
to produce a small shift in the apparent position of band edges. With
this correction, the surface band gap measured by STS is found to be
in good agreement with that obtained by other experimental and
theoretical techniques. Second, it is shown for the
SiC(0001) root(3) x root(3) surface that the tunneling spectra
show a remarkable evolution with decreasing current, and at pA levels
they reveal a Mott-Hubbard gap for the surface states, in agreement
with that seen by other methods. Finally, a detailed discussion is
presented on the absence of electronic effects for the tunnel current
into empty states of III-V (110) cleaved surfaces. From this result it is
demonstrated that one can use observed strain induced displacements of
such surfaces to yield information on the chemical composition of the
underlying material.
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