Surface photovoltages due to pulsed sources: Implications for photoemission spectroscopy

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Abstract
Photoemission spectroscopy experiments have shown that photons used to determine semiconductor band bending can induce measurable photovoltages. Because of the pulsed-photon source, the charging and discharging processes taking place at the semiconductor surface have been proposed as seriously affecting synchrotron-radiation photoemission measurements [M. H. Hecht, Phys. Rev. B 43, 12102 (1991)]. In this paper we present some illustrative experiments showing the effects of using a pulsed-photon source on the surface potential of n-type GaAs with a semitransparent Schottky diode. Implications for synchrotron-radiation photoemission results are discussed. We conclude that in these experiments the originated photovoltages are practically flat, and that they can be calculated from average photocurrent data, taken as effective restoring currents.