Landolt-Börnstein - Group III Condensed Matter Surface photovoltage spectroscopy


This chapter discusses surface photoconductivity and surface photovoltage (SPV) spectroscopy of semiconductor. Photoconductivity with light of sub-bandgap energy has been used to obtain spectroscopic information on surface states in semiconductors. In principle, both optical transitions from filled surface states to the conduction band and from the valence band to empty surface states can contribute to surface photoconductivity. SPV is the change of barrier height at a semiconductor surface induced by suitable illumination. The effect can be simply thought of as a voltage drop building up between the front (illuminated) and rear faces of the sample as photocarrier of opposite sign are separated by the electric field of the space charge region. The larger is the semiconductor energy gap (and the lower is the temperature) the higher is the SPV signal. Since the SPV effect depends upon the steady state density of photoexcited pairs and their separation from each other, the spectral dependence of SPV is certainly related to the absorption coefficient. However, an interpretation of SPV spectra in terms of absorption coefficient is complicated by other concomitant transport and relaxation processes. Moreover only part of the optical transitions contributing to the absorption coefficient is actually effective in SPV.

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Title Surface photovoltage spectroscopy
Book Title
Interaction of Radiation with Surfaces and Electron Tunneling
8.1.1 Introduction
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Landolt-Börnstein - Group III Condensed Matter
  • G. Chiarotti
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  • P. Chiaradia
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