University of Illinois Urbana-Champaign

Surface states on the cleaved (III) silicon surface

Aspnes, David Erik

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Description

Title
Surface states on the cleaved (III) silicon surface
Author(s)
Aspnes, David Erik
Issue Date
1965
Doctoral Committee Chair(s)
Handler, Paul
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • single crystal silicon
  • conductivity changes
  • silicon III
  • Fermi level
  • valence band edge
Language
en
Abstract
Conducti vi ty changes resulting when sing.le crystal silicon is cleaved in ultrahigh vacuum have been measured parallel to the cleavage plane over various temperature ranges for gold dope~ and high.resistivity boron doped silicon. The resulting change of conductivity is related to the difference between the valence band edge and the Fermi level in the bulk and at the surface, and to the quantity of charge in the surface states which has been trapped from the bulk. Analysis of the data shows a high density of surface states on the clean cleaved surface, centered 0.28 ± 0.08 eV above the valence band edge. The den- 13 -2 -1 sity~depends on the model chosen, but is at least 10 cm eV • Results obtained in this experiment are correlated with results obtained by other experiments. Oxygen absorption is observed to introduce different surface states, also of high density but centered 0.6 + 0.15 eV above the valence band edge of the surface. Low temperature measurements on gold doped silicon crystals show that probably no conduction takes place through the surface states themselves, either on clean or oxidized surfaces. These results are used to obtain possible models of the surface state distributions. A two dimensional conformal mapping is used to derive relations between conductance change and conductivity per square for several geometries, and to obtain corrections to the observed conductance change f.or cleavage planes not parallel to the initial current flow lines.
Type of Resource
text
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http://hdl.handle.net/2142/23963
Copyright and License Information
1965 David Erik Aspnes

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