scanning tunnelling spectroscopy abbr., STS (rus. спектроскопия, сканирующая туннельная abbr., СТС) — a family of scanning tunnelling microscopy methods which give information about local electronic structure of a studied surface by changing voltage between the tip and the sample.

Description

Since tunnelling current is determined by integration of all electronic states in the energy range related to voltage V (from zero to eV), varying the value of V we can obtain information about local states' density as a function of energy. The most commonly used method to obtain this data is to measure tunnelling current I dependence on voltage V at each point of the scan at a constant distance from the tip to the sample. This facilitates either calculating or determining directly, through the use of hardware differentiation, the voltage dependence of the so-called logarithmic derivative (dI/dV)/(I/V) which corresponds closely to the energy spectrum of electron states density in the sample. By this method, in particular, the spatial distribution of states' density at a given energy can be determined.

STS makes it possible to probe local electronic properties of a pre-selected and no matter how small, down to a single atom, area of a surface, which makes it possible to distinguish atoms of different chemical natures. Generally speaking, spectroscopic information is very useful when dealing with such issues as the band gap (see "energy-band theory"), bands bending at the surface, nature of chemical bonds.

Authors

  • Zotov Andrey V.
  • Saranin Alexander A.

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