Surface photovoltage and photoelectron spectra of GaP

Surface photovoltage (SPV) and photoelectron spectra (PES) of crystalline nn-GaP wafers have been studied at 300 K. The magnitude of the surface potential (Vs)(Vs) decreases in the presence of photons with energy more than the band gap, however the magnitude of VsVs increases in the presence of photons with sub band gap energy. The SPV spectrum is helpful in understanding the rigid shift of PES spectra of nn-GaP wafers towards higher kinetic energy in the presence of secondary white light from a tungsten lamp.