NEAR-BAND GAP TRANSITIONS IN THE SURFACE PHOTOVOLTAGE SPECTRA FOR GAAS, GAP AND SI SURFACES

The spectral surface photovoltage dependences of the clean GaAS(100) surface as well as the real GaP(100) and Si(111) surfaces have been investigated in the vicinity of the energy band-gaps. The spectral regions have been determined, where optical band-to-band direct (GaAs, GaP) and indirect (GaP, Si) electron transitions are dominant. From the graphical analysis the photothresholds of these processes have been estimated, consistent with the literature data.