Surface photovoltage in semiconductors under sub-band-gap illumination: continuous distribution of surface states

Surface photovoltage spectra in semiconductors are analyzed when the sub-band-gap illumination induces the electron transitions from surface states to the conduction band under the assumption that distribution of surface states is continuous. From analysis performed it follows that the fictitious densities of surface states can be induced due to the wavelength dependence of the photoionization capture cross-section of surface states for electrons and by the electron recombination capture cross-section of surface states which depends on the energy position of surface states in the energy gap. The high illumination intensity (laser illumination), which makes completely empty the surface states, can eliminate the fictious surface states when the density of surface states is not very large, the temperature of measurements is low, and the surface potential barrier is high. Received: 24 June 1998 / Accepted: 29 March 1999 / Published online: 14 June 1999