Surface photovoltage effects on p-GaAs (100) from core-level photoelectron spectroscopy using synchrotron radiation and a laser -: art. no. 155308

The surface photovoltage (SPV) effect on laser-excited p-GaAs (100) has been investigated using core-level photoelectron spectroscopy with synchrotron radiation (SR). The energy shift of the Ga 3 d photoelectrons due to the SPV effect was remarkably dependent on the sample temperature and the laser photon flux. The dependence in each case was well interpreted on the basis of a simple SPV formula derived from the band-bending scheme with excess photocarriers. The magnitude of the band bending was about 0.8 eV for clean p-GaAs (100) surfaces having no electrodes. Similar core-level shifts were observed in the Ga 3d and Cs 4d spectra of Cs/GaAs (100), indicating an unpinned behavior of the electronic states of the Cs surface layer, The time response of the SPV effect was also investigated in the nanosecond range using a pump-probe method with SR and the laser.